2 4 0 T U R B O . C O M
D A V E ' S   V O L V O   P A G E
And Classic Auto Air AC Installation Project

     UPDATED: June 20, 2024          CONTACT   
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240 Original AC INTRO
Stock 1991 and LATER 240 AC
240 AC Systems Overview
Later 240 AC Wiring Diagram
Using PROPANE (R290) in your AC
DURACOOL R12 Replacement
First Classic Auto Air
Installation in a 240 (2016)
Dave's Classic Auto Air
Installation Starts HERE (2017)
Classic Auto Air
vs Vintage Air
New Larger AC Ducts Installed (2021)
AC Hose Assembly
Traditional Crimp and Other Alternatives
Dash Wiring Basics
Charging with Refrigerant
RESULTS: 134a versus Duracool

Preventing Evaporator FREEZE-UPS
Evap Temp Controller
for Precise Temp Control

Before completing my new AC system installation, I first gutted the interior and installed DYNAMAT.
CLICK HERE to see the 240 DYNAMAT Installation Page
If you have any suggestions to improve the information in this page, please email.  Thanks, Dave

Volvo 240 AC
I enjoy taking long road trips. Taking a long road trip in a hot car in hot climate is not as much fun. So when I take a long road trip, how much better would it be if I had decent AC?
Getting satisfactory AC in an early 240 can be a real challenge.  I sincerely believe the AC systems in these cars were designed with only northern European climate in mind.
They were almost always a disappointment for U.S. owners in warm weather.  In older 240s ( pre-1991) the AC systems were just not up to the task.

Volvo didn't really try hard at first for a great result.  The 1984 Volvo 240 factory specifications called for AC output temperature from the center vents to be 48-54 degrees Fahrenheit. That's not cold.
The AC was later improved for 1991-93 cars when a differently design system was used (more below).

Image below shows a pre-1991 240 AC, showing an AC drier on the right fender.


So then is LATER 240 AC BETTER?
If Colder is Better, the answer is YES!

Thermal Expansion Valve versus Orifice Tube.
Later 240s made from 1991 to 1993 got a more modern system that can be recognized by the big silver aluminum accumulator/drier near the right side firewall.  These systems were a different design. These later systems incorporated an ORIFICE TUBE rather than a THERMAL EXPANSION VALVE (TXV) found in older systems. 
The 1991-93 system began using an Orifice Tube instead of a TXV, but retained R12 refrigerant through 1992. The 1993 models were changed to use the new R134a.
Image below of 1991-93 240 AC (showing larger accumulator/drier near right firewall).

Late 240 AC Components

Here's an overall image of the entire LATER 240 AC system along with a later style AC evaporator box, accumulator, compressor and condenser.
1985 versus 1993 Evaporator Box Comparison

The above image shows a side by side comparison of a 1985 (on left) and 1993 (on right) evaporator box. This view is of the bottom, showing the vacuum reservoir used for vent control functions.
The evaporator boxes are slightly different in a few measurements, but ultimately can be interchanged if you're up to the challenge of such deep dash disassembly.
Evaporator Coil Design Changes for 1991.

The 1991 and later 240 evaporator box under the dash was a different design and it used a more efficient evaporator coil inside (above). 
The first photo above shows the old style copper TUBE AND FIN design.  The second photo above is the more efficient and larger aluminum parallel flow coil design, which was used in 1991-93 240s.

240 AC hoses, couplings and fittings have always been standard SAE thread components. It has been reported that for 1993 ONLY, the accumulator on the firewall received METRIC THREAD fittings.
More general information about 240 AC systems can be found in the next section below.


I have some useful info on ORIGINAL versus NEWER style condensers in my CONDENSER SECTION further down in my page.

Introduction of the Orifice Tube in the 1991 240

Here's a photo of a 240 ORIFICE TUBE being removed.
An orifice tube or orifice valve is a restrictive valve which is meant to force the pressurized refrigerant to expand after it passes the restriction. The expansion of compressed refrigerant creates the cooling effect in the evaporator coil. An orifice valve is generally a metal tube with a chamfered inlet and with a plastic valve body.  It can become clogged or gummed up if debris or contaminates get into the system, especially if it was not in use or left open to elements, or in the case of a compressor failure. This valve can easily be replaced if it's questionable.
This photo above is from the following thread on converting an early 240 to a later AC system: https://forums.turbobricks.com/showthread.php?t=357795.
1363449 Compressor Relay (near AC switch).
1395590, 3513066 Compressor 240 to up 1992 R12.
6841028 Compressor 240 1993 R134a.
1370235 Accumulator/Drier 240 1990 R12 (RHD, LHD).
9144329 (1388667) Accumulator 240 1991-92 R12 (LHD-USA).
3540009 Accumulator 240 1991-92 R12 (RHD).
3540588 Accumulator 240 1993 R134a (RHD).
9131972 Accumulator 240 1993 R134a (LHD-USA).
3537866 Low Pressure Switch (pressostat) 1991-92 240 R12.
3537506 Low Pressure Switch (pressostat) 1993 240 R134a.
 3522250 Thermal Expansion Valve (TXV) 240 1990.

1324829 Orifice Tube Insert 240 1991-92 R12.
 3545086 Orifice Tube Insert 240 1993 R134a.
1214851 Evaporator Coil 240 to 1990 R12 (RHD, LHD).
3540231 Evaporator Coil 240 1991-93 R12 or R134a (LHD).
3522858 Evaporator Coil 240 1991-93 R12 or R134a (RHD).
1259556 Condenser before 1991.
3540373 Condenser 1992 R12.
3540647 Condenser 1993 R134a.
3540227 Condenser Fan Pressure Sensor/Switch 1991 R12.
6848106 Condenser Fan Pressure Sensor/Switch 1992 R12.
3540657 Condenser Fan Pressure Sensor/Switch 1993 R134a.
1323592 Condenser Fan Relay

Can I convert my old 240 to have later, more modern AC?
Yes you can. For those of you looking to convert an earlier pre-1991 240 to use 1991 or later AC components, here are some very useful discussion threads on this topic:
CLICK HERE to see a comprehensive WIRING DIAGRAM for later 240 AC BELOW.

240 AC Systems
General System Overview Information

If you want to learn more about 240 AC systems, then this information will help.
All 240s used SAE fittings in their AC systems (with one exception in '93). So this means that if you're repairing or making any new hoses, you'll usually need fittings with standard or SAE thread, not metric.
The ONE exception is the 1993 (one year only) 240, which reportedly used an accumulator/drier with metric threaded fittings.
<<< (7 page PDF 2 mb)
This is an excerpt from a 240 AC Greenbook.

It offers an explanation of the heater and AC systems offered in 240 models from 1975-1990. 

  The "Standard Unit" or "Standard Heater" was an AC delete system usually available only in countries OTHER than USA or Canada.  The "Combined Unit" (heater and AC combined) was the type of system normally offered in all cars imported to USA and Canada.  All AC systems in 240 models from 1975-1990 used R12 (Freon) refrigerant with a Thermal Expansion Valve (TXV) to control and release pressurized refrigerant into the under-dash evaporator coil.

<<< (5 page PDF 1.5 mb)
Here's another excerpt from the 240 AC Greenbook.

It offers an explanation of the CHANGES in 240/260 AC systems over a 15 year period from 1975-1990. 

<<< (3 page PDF 1.2 mb)
Here's another excerpt from the 240 AC Greenbook.

It offers an OVERVIEW of 240 AC systems for LATER models offered in 1991-1993.

These later 240s got a more modern system that can be recognized by the big silver aluminum accumulator near the right side firewall.  It incorporated an ORIFICE TUBE rather than a THERMAL EXPANSION VALVE (TXV) found on earlier systems. An orifice tube performs the same function of controlling and releasing pressurized refrigerant into the evaporator under the dash. 

From 1991-92 this system used R12 refrigerant. The 1993 models were changed to R134a refrigerant and some components were changed (orifice tube, sensors, new condenser and new high and low pressure service valves) to accommodate the new refrigerant.  Also, 1993 models received compressors with a temperature switch, which is designed to cut power if the compressor overheats (typically due to a leak).

240 Vent Control Diagram for Vacuum Lines 1981-93 240 (USA).
I created the below diagram because nothing like it exists anywhere in any Volvo Greenbook and many people needed to know where all those vacuum hoses in your dash go.

For more vacuum diagrams, go to my Vacuum Diagram Page

There are TWO pressure switches in the 1991-93 system. 

1. The image to the left is the accumulator/drier. It receives refrigerant as it exits the dash evaporator coil. Refrigerant passes through this accumulator before returning to the compressor.
A pressure switch is mounted on the accumulator/drier. It's a low pressure switch (or pressostat), which is designed to read internal refrigerant pressure of the refrigerant coming from the evaporator.  This switch controls compressor cycling and is designed to cut power to the compressor clutch when pressure readings from the evaporator drops below 23.2 PSI (for an R134a switch) or below 26.1 PSI (for an R12 switch).  It then allows the compressor to come back on when pressure exceeds 44.9 PSI (for an R134a switch) or exceeds 46.4 PSI (for an R12 switch). 

This switch is needed because when pressure in the evaporator drops below 23 PSI, the evaporator can get too cold, or cold enough to freeze the coil. Also any minute moisture or humidity on the outside of the coil will begin to freeze and may form ice. This has less of an effect if you're in a dry climate.  A sub-freezing evaporator coil may sound like a GOOD thing, but when it gets TOO cold it freezes up and ice will disrupt air flow through it and will cause poor AC cooling. Also, a sub-freezing coil will begin freezing on the inside if there is any traces of moisture in your refrigerant.  There shouldn't be any, but any time the system is opened, air can enter and air contains moisture. This is the reason behind vacuuming the system before installing refrigerant. It's also a good reason why an accumulator/drier should be replaced if it's old or if you suspect the desiccant inside can no longer effectively remove traces of moisture.

Low Pressure Switch (pressostat) 1991-92 240: Volvo PN 3537866.
Low Pressure Switch (pressostat) 1993 240: Volvo PN 3537506.

2. The other switch is a sensor in the high-pressure line between the condenser and accumulator. This high pressure switch turns the condenser fan ON when pressure increases to over a certain level.
Switch turns fan ON at 245 psi and OFF when it drops below 188 psi.
3540227 Condenser Fan Pressure Sensor/Switch 1991 R12.
Condenser Fan Pressure Sensor/Switch 1992 R12.
Condenser Fan Pressure Sensor/Switch 1993 R134a.
Excessive Pressure Safety Valves?
Contrary to what many people think, there is NOT an electronic HIGH PRESSURE switch in this system. Nothing electronic guards against over-pressure situations.  These systems all use mechanical pressure relief valves. Some compressors will have such a relief valve to vent gas in the event of an over-pressure situation. Depending on the manufacturer of the compressor, this "safety" valve will release pressure if it exceeds approximately 31 to 37 bar (450 to 536 psi). 

There is also a mechanical pressure relief valve on the high pressure metal pipe going to the top condenser port. The valve is a replaceable part, Volvo PN 3522398 (believed to be NLA).

If you have one of these cars and experience a vent release on a hot day, check your condenser fan. A failed condenser fan can easily cause pressures to spike high enough to vent refrigerant.

Refrigerant Service Valves

LOW PRESSURE SIDE:  The service valve (fill valve) for the low pressure side of a 1991-93 240 is located on the pipe coming from the firewall to the accumulator. This pipe is referred  as the evaporator outflow, low pressure pipe or suction pipe. For 1991-92, this valve was be configured for R12 equipment.  Adapter fittings are available to convert an R12 fitting to accept R134a style equipment.
For 1993 models, this fitting was reconfigured with R134a service valves.

HIGH PRESSURE SIDE:  Some rotary style compressors will have service valves on the back side.  Not all will have these. Some will have blocking plugs in those ports or no ports at all. In most later 240s it's common to find NO HIGH PRESSURE SERVICE VALVE under the hood.

Here's a comprehensive WIRING DIAGRAM I created for the 1991-93 240 AC system. 
CLICK the BELOW IMAGE for a larger photo.

Or click here for PDF version you can print or download (800 kb): https://www.davebarton.com/pdf/240-1993-AC-diagram.pdf

AC Compressor Relay PN 1363449. Located near AC switch in dash.

Condenser Fan Relay PN 1323592. Located under hood on left inner fender between battery and suspension tower.

Here's an alternate MODIFIED diagram below of the condenser fan for a LATER 240 fan circuit.
Normally the condenser fan only comes on when the Pressure Sensor is closed. Who wants that?
This modification diagram below changes TWO wires on the fan relay
(see the blue boxes below). This allows the fan to run anytime the AC Compressor circuit is activated and anytime the compressor is running.

R12 and R134a Refrigerants
R12 refrigerant was used in all Volvo 240s through 1992. Beginning in 1993 all 240s changed to R134a.
As previously mentioned, R12 was eventually banned in the U.S. and other developed countries in 1996 and then worldwide in 2010. 
R12 is dichlorodifluoromethane, a colorless gas sold under the brand name Freon, Freon-12 or R12. It's classified as a chlorofluorocarbon (CFC). This CFC part is why it was banned because it has been reported to potentially damage the Ozone layer..

Thermal Expansion Valves were used in all 240 R12 systems up through 1990.
It is commonly believed that thermal expansion valves (TXVs) used in these cars were specifically adjusted by the factory (or by the TXV manufacturer) for use with R12. Then later when one of these 240s got retro-fitted with R134a, it would get a replacement valve that was supposedly calibrated for R134a.  This raises questions about us DIY mechanics doing their own AC adjustments. Can we adjust a TVXs to suit R12, R134a or another suitable refrigerant. The answer has never come for certain.
This adjustment method on a TXV used in a Volvo is illustrated above.
With the TXV inlet port disconnected, an Allen (socket) wrench is inserted into the inlet port. There's a socket set screw with a spring behind it. That screw is is turned to adjust. 
There are many opinions on what these adjustments need to be for different refrigerants and so far NONE of it is definitive.
A discussion thread on setting these valves is posted below. Some people claim to know the answers about this stuff, but I'm convinced no one knows SHIT.
  TXV Adjusting thread:

When Propane is used as a refrigerant it's designated as R290.  Propane has been used for many years as a refrigerant all over the world.
Yes, there can be a difference in purity between Propane fuel and R290 used for refrigeration. More about THAT in the R290 Section.

Over the years of owning 240s I have done my share of experiments trying to improve 240 AC performance. I knew nothing about auto AC at first. I started off slow and gradually learned how the systems worked. I eventually began trying new things.
Some experiments have responded fairly well, but were mostly a disappointment. None would seem to work as well as my idea of what a real modern AC system is supposed to do.

Beginning in 2010 I began making a serious attempt at using PROPANE as a refrigerant. This was a suggestion by another 240 owner I knew who claimed to be successful with Propane in his 240. I knew nothing about it at the time, but I was willing to give it a try. 
Propane is a fuel that's produced in the crude oil refining process. It's made up of 18% Hydrogen and 82% Carbon. This is why it's call a "Hydro-Carbon" (i.e.: HC).

My success with propane years ago was limited to some pretty good cooling on the highway (most of the time), but there were always problems during idle when the cooling would gradually taper off and go away. It was very frustrating. Other times there were also suspected problems with things freezing up from getting too cold, which caused more temporary failures. At one time I crawled under the dash and used my laser temp reader to measure the evaporator temp. It registered 17 degrees Fahrenheit. This is too cold. It probably contributed to suspected freeze-ups and the intermittent failures, but I didn't have the experience at that time to deal with it or confirm it. During this time I did have success with helping a friend convert a totally stock '84 240 GL from R12 to Propane AC. That car worked well for many years at idle and on the highway.  So it appears that some cars just respond better than others. My '84 242 Turbo did not respond to Propane as well as I had hoped. 

I built this service hose above so it would connect to my service valves and manifold gauges.
In the above right photo I added a fitting for a small 1 lb. propane bottle. The smaller fitting above is for an R12 service fitting, since at that time my car still had original R12 fittings.
This custom hose was made using simple pneumatic air hose and fuel injection hose clamps. This type of hose is more than adequate for the pressures of an AC system.
A 1 lb. propane bottle will typically have a maximum pressure of about 120 PSI when full.

Some brief info about AC FREEZE-UPS
There can be TWO different types of freeze-ups in an auto AC system. 

One occurs when trace amounts of moisture in the ambient air begins turning to ice on the OUTSIDE of the evaporator. This can happen when the outer surface of the evaporator drops below freezing. Small amounts of frost forming on it will not cause problems. When the frost or ice melts, it'll drain out to the bottom of the car, which is pretty normal for any AC system. If the evaporator gets or stays cold enough for too long, ice can begin forming in abundance. If enough ice forms, it will eventually block the flow of air going through. You'll get poor airflow through the vents and any air that you get will not be very cold. I'm pretty sure I never experienced this type of freeze-up.

Another type of freeze-up can occur if there is trace moisture INSIDE your system and if the evaporator dips below 32 degrees Fahrenheit.  When the refrigerant temperature drops below freezing, any traces of moisture can crystallize (FREEZE) as it enters the evaporator tubes. If enough ice forms, it will temporarily block the flow of refrigerant into the evaporator.  If this occurs, then a symptom will be no more cool air from your vents. Another symptom would be reduced pressure in your low pressure side line (which is between the evaporator and compressor).  The reduced pressure can even become a vacuum if the blockage is severe. This condition is temporary and it'll slowly thaw out when you let the car sit for a while. This second type of freeze-up can be prevented or reduced by thoroughly vacuuming your system to remove air (and moisture) and also by replacing the receiver/drier (which contains a desiccant for moisture removal). 

An old receiver/drier can become useless if the desiccant becomes saturated with moisture. This can easily happen if the system was left open or it the receiver/drier was sitting on a shelf for a long time and the seal was not 100% air-tight. If you open a seal on a new receiver/drier and you don't hear the "PSSSSST" of rushing air, then it was not properly sealed.

This FREEZE-UP concept is something my self-taught amateur brain didn't comprehend during those propane experiments years ago.

FREEZE-UP SECTION (click here).


Here's a service hose made to work with a Propane or Butane bottle. I've included a 1/4 NPT ball valve and an R134a service fitting. The postal scale above is a needed tool so that you can precisely measure the weight of refrigerant as it leaves the bottle.  An efficient Propane/Butane mix proportion is not set in stone. I think every car may be a bit slightly different and some experimentation may be needed. So far it appears a mix somewhere near 50% Butane and 50% Propane ( about 30%) will get some decent results.  The perfect "sweet spot." of that mix is not really known to me, but like I said, I think it may be different for each car. 
DIY Mixing R290 (Propane) with R600a (iso-Butane)

  You'll notice in the Duracool section below that this Propane/Butane mixing is how Duracool is made, although I don't know what proportions they use. They probably keep that a secret.
Here's is a rather obscure video below, which suggests the best cooling efficiency is 50% of each.


Here's a video below (from 2015) on the DIY use of Propane (R290) and mixtures with Butane (R600a). He is using it as an alternative to R134a.
Spoiler Alert: This guy in the video eventually settled on about 30% Propane and 70% Butane as the best combo for HIS car for cold AC.
Your results may vary.


There is an extensive (old) Turbobricks thread here if you want to see more on adventures with propane:

(Hydro-Carbon Refrigerant MIX)

In 2012 gave up on straight propane and began trying Duracool 12a replacement http://www.duracool.com/
I later learned that Duracool is a mixture of Propane (R290) and Butane (R600a). The precise mixture is not known by me and it's probably kept secret by Duracool. The addition of Butane in the mix seems to be the ultimate key in making it more consistent than propane alone. My introduction to Duracool was many years before I changed to Classic Air AC and I spent a lot of experimental time trying to get it dialed in. I tried a number of different thermal 240 expansion valves and a LARGE number of different expansion valve settings. My 240 eventually got pretty good cooling on the highway, but I still found intermittent problems at idle (although it seemed to get a little better than with just propane). I kept experimenting over the years with many different expansion valves and a huge variety of TXV settings, hoping to find the right combination that worked.  Things never got great and ultimately I remained less than satisfied with my AC.


It appears the availability of R12 SUBSTITUTE refrigerants in the USA is being threatened by the US EPA.
In 2023 I began noticing that some R12 substitute companies, such as Enviro-Safe, have REMOVED all hydrocarbon (HC) R12 substitutes from their web pages. Some pages have mentioned this is the result of new US EPA SNAP regulations that became effective in May 2023. I have not noticed any restrictions in sales in the Duracool page.
Here's the EPA bulletin: https://www.epa.gov/snap/unacceptable-substitute-refrigerants
Here's more about what is considered an R12 substitute (HC-12a): HC-12a Wikipedia

So what can YOU do as an amateur DIY AC tech?
You can do plenty. I've already begun some experiments of my own with mixing Butane and Propane. You'll see some info below of blending the two. I think a 50/50 mix of the too is a good place to begin.
 When I began trying this, I noticed that when beginning with Butane, I noticed it would cool, but the reduction in temperature was be slower. Then as I began adding Propane, that reduction in temperature sped up rapidly. So increasing the percentage of Propane to Butane made it COLDER, to a point. It's important to plan ahead so in the end you don't overcharge your system. If you goof, you need to start over. A good chart to use to understand how much TOTAL WEIGHT of Butane/Propane mix to use is in the Duracool chart HERE.  For example, my custom system is designed for 24 ounces of R134a. The Duracool chart shows the equivalent for me is only about 9 to 10 ounces total. So if you try a Propane/Butane mix, try not to exceeds that amount.
A 1986 240, which uses about 2.9 lbs of R12, should only need about 16 ounces of Duracool or Propane/Butane blend.
A 1993 240, which uses about 1.63 lbs of R134, should only need about 11 ounces of Duracool or Propane/Butane blend.

I use a digital postal scale to weigh a canister as the refrigerant is being charged into the system, so I can see ounce by ounce precisely how much is going in..
Keep in mind that I've read some opinions that say some Propane available for automotive fuel may already have a percentage of Butane already in it.  I don't know how you can test for or avoid that. The prevailing opinion for a typical 1 lb. propane canister you find at a store is that those are usually fairly pure Propane, but maybe not the purest you can get. Reportedly the purest you can get is classified as R290.

The ultimate goal for cold AC is to get an evaporator temperature as cold as possible, but to stay above the temperature where a freeze-up can happen. Staying above 32F (0
C) may be a good goal to avoid freeze-ups. If you cannot find a way to measure your evaporator temperature, then measuring vent temperature will be the next best thing, but read here for how I measure and regulate my evaporator temperature. Charging an auto AC system yourself and mixing two different chemicals is not difficult if you can competently use an AC charge hose and a postal scale.


If you search for information, you'll find a lot of opinions. Some will tell you that you must INVERT a Propane can when charging and install it as a LIQUID or the AC won't cool. I think this is B.S if you're installing ONE chemical.
Inverting a can and charging as a LIQUID is generally recommended for refrigerant MIXES, such as Duracool (a mix of propane and butane), or any refrigerant which is made up of two or more chemicals.  This is so the mix stays in MIXED FORM as it's installed. The concern with mixed refrigerants is  that if you install it UPRIGHT as a GAS the mix might be uneven. The lightest gas might evacuate first. Propane is a single component chemical and not a mix. It's made of hydrogen and carbon molecules and those will not separate into just hydrogen or just carbon on their own. So installing Propane upright as a gas is ok.

Choosing Ordinary Propane or R290 Refrigerant?
Should you buy cheap Propane fuel or more expensive R290 refrigerant? What about Butane or R600a (iso-Butane)?
If you decide to buy R290 you should expect it will probably be a more PURE form of propane than normal fuel propane. R290 is refined specifically for refrigeration use. It will have less moisture content and it has NO GAS ODORANT added.
Buying R290 or R600a will be more expensive, but it should be better stuff as long as you buy from a reputable source. How much better is something I can't say.
Enviro-Safe offers cans of refrigerant grade R290 and R600a (Iso-Butane).


Important criteria for R290:
Minimum Grade 2.5 (99.5% pure). Water content, <10 ppm water in the liquid phase. The use of the product name R290 followed by U.L. Classified indicates Underwriter
Laboratories has tested and evaluated samples of a product with respect to certain properties.
Always refer to the product Safety Data Sheet for more specific information.
Resource: https://www.hrai.ca/uploads/userfiles/files/R290%20Propane%20GR2_5%20UL%20F.pdf

If you have done your own Volvo AC upgrades or if you're planning to do something like this, please email me.  I'd like to hear about it.  
Also, if you have any suggestions to improve the information in this page, please email.  Thanks, Dave


If you're learning about testing or charging your AC s
ystem, here's a pretty good video that will help with the basics.


Aftermarket AC Systems for a 240
Over the years I would come across custom hot rods at car shows with custom aftermarket AC systems. These were usually from Classic Auto Air or Vintage Air.  I was very interested in the results and I would interrogate the owners about how well they worked.  I'm a SKEPTIC by nature and I remember the old JC Whitney catalogs many years ago, which had cheap under-dash AC systems.  JC Whitney did not have a reputation for high quality stuff and I never actually tried any of their AC systems. So my skepticism tended to pollute any confidence I might have developed in a retrofit aftermarket AC system.
The answers I got, however, from every one of those hot rod owners about their Classic Auto Air or Vintage Air systems were surprisingly very positive.

So then in 2016, after Michael Yount told me he had successfully installed a new Classic Auto Air system in his 240 (below), I paid attention and started seriously re-considering an aftermarket system.

CLASSIC AUTO AIR installed in a 240.
First came Michael Yount's 240 Installation.
This is what began changing me from a skeptic to a believer that real AC in a 240 was possible.

<<< In 2016 I learned that 240 owner Michael Yount of North Carolina had fitted a Classic Auto Air system in his LS3 equipped 1982 240.

Michael's car is featured in my Favorite 240 Page: https://www.240turbo.com/volvo240.html

Michael reported exceptional results with 36 degree vent temps at idle in 90 degree highly humid days. 36 degrees is way better than I could get consistently with my old 1984 240 AC. His success was enough to inspire me to make future plans for a similar installation. I don't think I would have ever considered such an installation if Michael hadn't done it first and I would have probably stayed in Volvo AC hell. 

Here are some pics below that Michael sent me showing some details of his installation.
This AC evaporator box is the Street Rod Cooler III from Classic Auto Air.  The shape of the aftermarket evaporator box is different from the original 240 box.  In this photo, you can see that Michael has added some of his own metal bracketry for mounting the new box under his dash. Also the sheet metal brackets at the very top are the same brackets in your 240 that hold the original box in the car just under the windshield cowl. 
Classic Auto Air has several versions and sizes of AC evaporator units. This is one of their all electronic boxes.  An electronic box like this one eliminates all cable and vacuum controls originally found in a 240.  So this means your 240 duct vents and temp controls are done electronically and all those original vacuum buttons and cable controls go away. 

 With the old evaporator box area completely gutted under the dash, here's a view of Michael's car with the new Classic Auto Air box sitting under the dash.  The design of this box is more compact than the original Volvo box. It's MUCH WIDER and LESS TALL than the original Volvo box.

Here's a front view of the new box in Michael's dash.

There are some compromises with this system you should know about.
As you can see above, the new evaporator box is wider than an original 240 box, so part of it can now be seen extending into the passenger footwell. The plastic on that center kick panel needed a little trimming to accommodate the blower motor. This is a small trade-off that I was willing to accept. 

The width of the Street Rod Cooler III unit is 20.875 inches (more info and dimensions found HERE). 
Michael reported that his installation did not require any modification of the dash or glove box. The only mod was some trimming on the kick panel.
Classic Auto Air also has one larger AC unit (named the "Custom Colder"), which is 3.125 inches wider, 0.5 inches taller and 1.6 inches deeper than this one.  Michael believed fitting that larger box would have probably required cutting into the glove box.

Another Compromise to Note: 
This system will NOT accommodate the original FRESH AIR VENT below the cowl, under the base of the windshield. This means there is no outside fresh air setting for this system.  It will only recirculate air inside the cabin.  So if you really need fresh air, you'll need to crack a window or open your lower kick-panel vent. Running fresh air through this AC unit is not possible. 
That original fresh air hole under the cowl will need to be closed off and sealed to keep the wet weather out of your car. Details about this are shown in this page. 

As you can see here, the old original 240 slide controls and vacuum push buttons are gone. 
In their place is a new electronic control panel with knobs.  It has fan speed, vent selection (front vents, upper defrost, and lower heat) and a cold/warm temp knob.

Try not to be confused when you browse Classic Auto Air's web pages. They also show setups using some CABLE controls, but they don't explain very well why they show both setups.  Basically the cable controls they offer are designed for classic cars where the owner wants to retain the original look of vintage cable controls.

Before completing my new AC system installation, I first gutted the interior and installed DYNAMAT.
CLICK HERE for the 240 DYNAMAT Installation Page
  If you have any suggestions to improve the information in this page, please email.  Thanks, Dave


Classic Auto Air Installation in my 240
Began in 2017.

Introduction to the Street Rod Cooler III
Street Rod Cooler III. PN 1-1091. Price in 2017: $685.00.
Update: As of May 2021 CLASSIC AUTO AIR has replaced this unit with the Street Rod Cooler IV for $799.00.
Width: 20.875 inches
Height: 9.5 inches tall
 Depth (front to rear): 7.125 inches.

Classic Auto Air's webpage and catalog is mainly focused on tailored kits for vintage domestic cars and a some targeted vintage foreign cars. There is a small page on universal AC kits, but I found it to be sadly light on real usable info for anyone looking at this as a fully custom installation like I was.  They could improve things by adding more info about full custom or non-standard installations. I had to hunt through different places in their pages to find useful info. I hope they begin adding more photos, explanations and more general info for custom stuff.

These custom units can be found by clicking on their Universal AC Systems link. Aside from the awesome information I got from Michael Yount, I learned the most by thoroughly reading the Classic Auto Air installation instructions (where the illustration drawing above came from).  They have a link to some PDF file downloads at the bottom of their web page. 

Classic Auto Air systems use Thermal Expansion Valves (TXVs) to control refrigerant flow.

Update NOTE : Considering the price increase noted above, you might also explore VINTAGE AIR. When I began this project, there was pretty much ZERO detailed info available about the differences between the two systems. One difference I have NOW become aware of in VINTAGE AIR systems is larger dash duct outlets on the unit: Vintage Air uses 2.5 inch ducts instead of 2 inch ducts in CLASSIC AIR outlets. I don't know how much of a difference this makes in the Vintage Air system, but I suspect the larger duct helps the airflow.  UPDATE NOTE: I later upgraded my duct hoses to 2.5 inch for the rear facing dash vent improve flow.  That can be seen HERE.

I've included some more info about a comparing units from Vintage Air BELOW: Click Here.

Heater dumps are these two 90 degree plastic ducts which redirect air to the floor. These were provided by the manufacturer with this evaporator unit.

The Heater Air Dumps are removable and optional.  So you may run the air dumps OR use normal duct hose from those outlets to your lower heat vents if you like. The heater air dumps simplify things if you decide not to run duct hoses. When using heater air dumps, the heat will simply be pushed down and out below the dash through whatever openings exist.  This works just fine in a 240, so my installation uses these simple heater dumps instead of long duct hoses.

CHANGE NOTE: Before final installation I moved these HEATER DUMPS to the two INSIDE rear duct outlets (like this photo below). This allowed me to put the duct hoses going to my dash top defrost vents on the outer ducts. That gave me more room for those flexible duct hoses.

There were not many photos of this unit in the Classic Auto Air site, so I have included some here.

 Included with the above AC unit was an ECU and wire harnesses for making this thing work.

I also got this electronic water valve with my kit. It was included in the price of the Street Rod Cooler III. It's controlled by the ECU in combination with the temperature control knob.  It's designed to allow metered amounts of water for precise heat mixing. There's an orange label showing which end goes toward the heater core and a green label showing which end goes to the water pump.  IGNORE THESE LABELS!  They make no sense for a Volvo with a Volvo engine. See the correct orientation further below: CLICK HERE.

Classic Air offers control panels in a few different styles and finishes. It is NOT included in the basic AC unit price. I chose this black anodized knob set in a horizontal configuration. 
PN 16-2136.  Price: $175.00.

In this image you can see that I've made a clean control panel to hold the new controls.  I made this using the old panel and I added a sheet of ABS plastic.

Classic Auto Air offers kits and many individual components in their PDF catalog.  You'll need to hunt through their site to find their PDF catalog and the separate price list. 
They offer Sanden rotary compressors if you need one.  I didn't buy one from them.

An early 240 like my 1984 originally came with a York compressor like this one above left, which came in all 240 models before 1985.
A newer rotary style compressor (ABOVE RIGHT) is better, quieter and more efficient. This newer style was originally equipped in 240s beginning in 1985. My 1984 240 had already been changed to a new rotary style compressor back in 2002 by the previous owner. That compressor was beginning to get a little noisy after 15 years, so for this project I purchased the above new rotary compressor from FCP Euro, Volvo PN 8251069.


Note that when you're shopping for a compressor, you may find two (or more) different port configurations.

My 240, which had a later compressor update in 2002, used the straight up ports above LEFT. Some compressors have a "V" port configuration, shown above RIGHT (Sanden).
Considering how stiff AC barrier hoses can be, getting one configuration to fit a different one may be hard, unless you're open to making new hoses. 

And some newer style compressors may be found with very different style fittings on the back, requiring a bit more of a challenge.
Photo above from Aris (from Greece) 240 build thread: turbobricks.com/6329767


The above photo is from Aris (from Greece) taken during his 240 build, which can be found in his thread here: forums.turbobricks.com/310632.
The above photo shows the original black 1985 240 condenser, which is made from TUBE and FIN construction. All 240s up through 1990 received a black condenser similar to this one. The original size was about 15.5 x 26 inches.
Aris then fitted a new 16 x 24 inch universal PARALLEL FLOW CONDENSER, also shown above.
TAKE NOTE that the hose fitting sizes for IN versus OUT on a condenser are not the same size. The top one is larger (#8 male) and is connected to the hose going to the compressor. The bottom fitting is smaller (#6 male) and is connected to the hose to the drier canister on the right fender.  I have more info about AC hose sizes further down in my AC build or CLICK HERE.

If you're wondering what a PARALLEL FLOW CONDENSER is, it's basically a newer and better design than the original tube and fin style condensers. A parallel flow type is reported to be about 30% more efficient.
You can buy one from Classic Auto Air or Coldhose (where I bought mine) or a variety of other places if you search for: Universal AC Condenser.  A universal condenser will be available in different sizes, but one in the approximate size of about 16 x 24 inches like the above one will fit OK in any 240 (or see below for the larger 16 x 26 inch condenser I installed). 

Later Factory 240 Condenser

If, by chance, you have a 1991-93 240, you should already have a superior parallel flow condenser, like this 1991-93 240 condenser shown above. This one above is unpainted, but typically the factory condensers were BLACK.
If you have the older tube and fin style (below), you can install a later one like this above with a bit of work, or you can buy a universal type that may or may not fit without a lot of work.

The design difference is pretty easy to see compared to this early style condenser above, which came out of a 1990 240.
I know you'll want to know this: A straight swap may not be always be possible.  The locations or positions of factory AC hoses may not be quite the same between the two styles in a 240. The Volvo factory was not always consistent. Plus if you compare this condenser to the 1985 condenser further up above, you'll see the hose connections have changed over the years. So please understand you may need to change or create some hoses. If creating hoses is needed, you can read more about creating AC hoses further down or CLICK HERE.


As shown ABOVE, Aris mounted a 16 inch low-profile Spal PUSHER fan on the front of his universal condenser. Spal fans are an excellent choice and are very well made and very powerful. A good pusher fan is recommended to get better air flow when you're stopped or at low speeds. 

Here's a photo below of my universal condenser in my 240. The size I chose was 16 x 26 inches, which I bought from Coldhose.
A single pusher fan would be fine, but in my horrible endless obsession for colder AC, I installed dual 11 inch pusher fans, which I mounted to my condenser. 

If you're wondering why my horns are missing, I tossed them and then mounted some more serious horns under the car. 
I have a HORN PROJECT PAGE for that.

Mounting the new AC Box in the DASH.
Custom Bracketry Fun.
I began fabricating some mounting braces similar to those shown in Michael Yount's photos.  My technique was a little different from Michael's, so you can compare and choose the style you like. 
  The new evaporator box comes with some mounting points with U-nuts installed on the backside.  Basically I made some braces to make the box sit about 2 to 2.5 inches above the transmission hump and roughly 4 inches back from the firewall.  I originally wanted it to be closer to the firewall, but the heater hoses coming in through the original location were in the way. If you're planning a similar installation, you might consider moving the heater hose ports to a higher location, if possible. They can't really be move to the LEFT (driver side) any more than they are, because then they'll interfere with the accelerator pedal. So moving them up might be an option.

The kit came with some clear drain tube for the condensation drain on the bottom of the box, but it wasn't very flexible and tended to kink in a turn. So I used some silicone tubing I had on hand (that blue hose in the pic).

I used 1/8 inch thick aluminum bar stock I had on hand. It can be found in most hardware stores.  I chose aluminum because it's so much easier to work with than steel.

I used some clip-on barrel nuts (also known as U-nuts) that I had from some previous projects. I bought them from McMaster-Carr, PN 95210A150. Thread pitch is metric: M6 x 1mm. These are made for a panel thickness of 0.8 to 4 mm.
The bolts I used are McMaster-Carr PN 98093A436,
M6 x 1mm, 16mm long with a flange head. These are pretty much identical to the typical metric bolts with a 10 mm hex head that you'll find in your 240.

Here are some more views of the mounting braces I made.



The above photo is a view of the underside of the cowl (looking up) just below the center of the windshield.  This is where the fresh air cowl vent was located.  I have closed it off and sealed it. Not because I hate fresh air. It's because the new AC box isn't designed to accommodate a fresh air vent and if I didn't seal it, I would have water coming in when it rained.

I began by cutting a rigid piece of plastic to the precise shape of the hole. It helped to make this piece out of cardboard first. Then after I had the cardboard size just right, I transfer the shape to the plastic (or you can use metal or whatever material you decide to use). Then I applied a generous bead of 3M black Super Weatherstrip Adhesive around the edge and installed it.  Then I further sealed the opening with some Dynamat.

Those two brackets in this photo are the original sheet metal brackets which used to hold the top of the original heater/AC box.  As Michael did, I used those brackets as top mounts to help secure the new Classic Auto Air box.


After an endless number of in and out test fittings and adjustments of the new AC box with the bracket frame-work and top bracket pieces in place, I finally felt comfortable about the positioning.  I pushed the unit as far to the left side as possible and it's actually resting up against the driver's side inner kick panel. I trimmed some of the plastic off the top of the driver's kick panel to clear the actuator motor and thermostat, which now extends a little past and above the kick panel, but it's high enough to be above the under-dash panel covers and they're not visible after installation.

Here's a basic illustration of how this unit fits in my 240.

This photo is looking down at the 240 transmission hump near the firewall.

 The original condensation drain hole was in a difficult position for my preference, although it appears from Michael's photos he used it in his installation. I decided to move the drain grommet to the other hole (which had a closed grommet) as shown here, basically trading grommet locations.

Here's a look at the two  top cowl mounting points. I've connected them to the new AC box brackets I made. 
UPDATE: You should note that I made a last minute change and moved the HEATER AIR DUMPS from the OUTER rear air outlets to the INNER REAR OUTLETS (photo below), so now they are right next to each other.  This was a suggestion by Michael Yount. It helped to provide more clearance for the defrost duct hoses, which were placed on the rear outer outlets. 

If you're confused about how I could swap the heater dumps to the center outlets, this would be a good time to tell you this unit does not independently select defrost or heater vents.  It sends air through both lower heat and upper defrost ducts equally whenever the upper or lower vents are selected. So when ducting is added, it really doesn't matter which outlets are used for upper defrost versus lower heat.
You can add this to the trade-offs mentioned earlier.

This was a pretty small disappointment when I found out, but I got over it. It's not really a big concern for me, since I bought this unit for the AIR CONDITIONING, not the heating/defrost selection.


Biggest unit they offer.  In case you want something BIGGER.

As mentioned before, one of the compromises in this Street Rod Cooler III unit is it will not control the upper defrost and lower heater ducts independently. If you think you really must have these controlled independently, there's a larger AC unit from Classic Auto Air called the "CUSTOM COLDER" unit, shown BELOW.  This is their largest unit and it will do the defrost and heater vents independently.
As mentioned earlier, this unit is larger:
24 inches wide, 10 inches tall and 8.75 inches deep (front to rear).
This unit is 3.125 inches wider, 0.5 inches taller and 1.6 inches deeper than the Street Rod Cooler III unit I chose.

This larger unit should still fit in a 240 dash pretty well, except it would add ANOTHER 3 inches of airbox width that you can see under the dash in the passenger foot well. I'm not certain, but it could also interfere with a the back of the glove box, depending on how far forward or how far up the unit was mounted.

Large "CUSTOM COLDER" unit from Classic Auto Air

Here's an approximate illustration ABOVE of how I think this Custom Colder unit should fit in a 240.
And you can compare that to how my Street Rod Cooler III fits below.

Are there Comparable Units from VINTAGE AIR?
Pro's and Cons.

When I began this project, there was pretty much ZERO info available about the differences between Classic Auto Air and Vintage Air.
I've done a bunch of research since then. Vintage Air makes a comparable unit that you might also consider.
When I first tried to learn more about the differences, the ONLY info I could find was from people who were either 100% loyal to Classic Air or 100% loyal to Vintage Air. That was useless. For a long time I could not find any OBJECTIVE opinions from anyone who was familiar with BOTH. 
Since my installation, I have slowly learned a bit more about the differences.
Classic Auto Air advertises that they have a larger evaporator coil in their units.
Another important difference I'm NOW aware of with VINTAGE AIR systems is they have LARGER dash duct outlets on their units, which support 2.5 inch duct hoses instead of 2 inch duct hoses in Classic Air dash vent outlets. I do know this potentially makes a difference with airflow on a HIGH setting. 

Here's a useful comparison discussion thread of units from BOTH companies you can read:

Gen II Super from Vintage Air.

As of May 2021 this Gen II Super (Heat, Cool and Defrost) above from Vintage Air was priced at $510.00.
This unit is about 3 inches wider than the Street Rod unit I used. 
Dimensions: 24 inches wide x 8.5 inches tall x 8.5 inches deep.
NOTE: The Vintage Air unit does appear not have separately controlled heater ducts.  Heat will be directed to the dash vents or to the defrost independently.


Here's an approximate illustration above of how I think this Vintage Air unit would fit.
And you can compare to how my Classic Air Street Rod Cooler III fits below.

Here you can see how much of the Street Rod Cooler III unit can be seen under the dash in a 240 (photo of Michael Yount's car below).
Would another 3 inches of airbox width under there be too much?  Probably not.

Another Interesting VINTAGE AIR Distraction
Installation in a Classic Mazda

This is AaronCake below from YouTube.
He has a huge number of videos where he has spent years restoring a 1976 Mazda RX5 Cosmo. The reason I'm putting his info here is because he has several videos of the installation of a VINTAGE AIR AC unit in that car.
It's a smaller AC unit compared to those discussed above. The Mazda is much more compact than a 240. These videos offer a great introduction to a full custom installation of aftermarket AC.
In my opinion, this installation makes my Volvo installation look easy by comparison.
Part 29: Vintage Air Gen II Compac HVAC Install, Part 1 - My 76 Mazda RX-5 Cosmo Restoration

Part 30: Vintage Air Gen II Compac HVAC Install, Part 2 - My 76 Mazda RX-5 Cosmo Restoration

Part 31: Vintage Air Gen II Compac HVAC Install, Part 3 - My 76 Mazda RX-5 Cosmo Restoration

Mounting and Wiring.
Here are some views of the lower transmission hump mounting point that I mentioned above.  You can also see here in my installation there is about an inch of clearance between the new AC unit and the back of the lower console storage/radio enclosure. There are no critical clearance issues here. There seems to be plenty of space.

The electrical distribution block you see attached to the lower storage/radio enclosure will be discussed in more detail further below in my wiring section. It's used as a central location for all the dash grounds instead of mounting them to different bolts all over the dash like Volvo did. This is part of a wiring cleanup project that was badly needed.

  Close-up of the lower mounting point and small bracket I made and bolted to the bolt hole that used to hold the original AC box.

And a pic showing a view from between the seats.  As mentioned above, the AC unit is positioned as far to the left side as possible and is resting against the driver's side kick panel. It can't be moved more to the left without moving past the driver's side kick panel and interfering with your accelerator foot.

At the 240 firewall, the TOP hose always comes from the cylinder head. It feeds hot coolant to the heater core when heat is needed.
The BOTTOM hose is considered to be the RETURN HOSE and returns coolant to the water pump metal pipe which begins behind the engine and goes to the back of the water pump.


Here I've installed the electronic water valve for the heater function and I have plumbed the heater hoses. The hoses come into the cabin through the original firewall location just to the right of the gas pedal.  I used high quality reinforced silicone 5/8 inch heater hose. 
NOTE: The valve WATER FLOW direction for this photo ABOVE is from RIGHT to LEFT. This valve is installed in the RETURN LINE that goes from the AC box (heater core) to the BOTTOM HOSE at the 240 firewall, which returns coolant to the water pump pipe on the engine.
The following link shows instructions for a different AC box than I used, but it has the correct instructions for this valve:

This water valve can be placed pretty much anywhere. Classic Auto Air's instructions show it being installed in the engine bay, but I wanted it behind the dash instead.  The gray foam wrapped around the bottom of the valve is some leftover Dynaliner foam to keep it isolated so it doesn't rattle.  Any little thing you can do to eliminate rattles in a 240 is well worth the effort in my opinion
This illustration ABOVE is from Classic Auto Air's instructions.
The correct direction of coolant travel must ALWAYS be AS SHOWN by the ARROW above.
This valve should be installed in the RETURN HOSE going from the AC box heater core to the water pump suction/return pipe on the engine.
For this new electronic valve to be used in a 240, the RETURN HOSE comes from the AC box and goes to the above valve INLET
marked with the ORANGE label that says "heater core." 
Then the GREEN labeled valve outlet, marked "water pump," goes to the BOTTOM 240 firewall hose, where coolant
returns to the water pump pipe behind the engine..

Regarding the identification of the coolant inlet and outlet on the new AC unit heater core, Classic Auto Air does not specify which one is the inlet or outlet, so I chose the inlet and outlet by the best way the hoses seemed to fit.


Here's the ECU for the new AC unit. If you look closely you can see it sitting on top of the lower storage/radio enclosure.  It also has some Dynaliner foam that I stuck to the bottom and sides to isolate it from vibration or rattling.

2021 Update: Larger Ducts Added (click here)
The duct outlets on this new Classic Auto Air unit are designed for 2 inch flexible tubing.  They sent me 15 feet of 2 inch tubing with my kit (like the image BELOW). The tubing fits on the oval ducts snugly.

I contemplated for a while how to adapt this tubing to the Volvo original front dash and top defrost vents. I didn't need to
worry about the lower heater vents, since I was using heater air dumps instead of duct hose there. 

Also you may have noticed, the original Volvo heater lower ducts SHOWN BELOW (going under the carpet and under the front seats to the rear floor) were removed when I was applying Dynamat. Those vents were not needed and are now gone permanently. 

Here's an image from Classic Auto Air's catalog. It shows a number of duct adapters.
They sent me a few different adapters with my order that they thought would come in handy. Some did. some did not. Below I've detailed what I used and what I didn't use.

<<< They sent 4 of these and they came in handy for my defrost vents.  Strangely, these were NOT shown in their catalog. They are similar to PN 2-2028-4 in their catalog. The adapters I got were listed on my invoice as PN 0069-4. Cost was $12.50 each. SIZE: I measured them as 5 1/8 x 2 x 2 5/8 inches with an oval tube inlet made for 2 inch hose.

<<< They sent 2 of these. These are defrost vents shown in the catalog image as PN 2-1050. Cost was $17.50 each.  SIZE: 6 3/4 x 4 inches. The top defrost outlet is about 5/8 inch wide.

I did not use these.

Michael Yount said he used some DIFFERENT defrost vents supplied by Classic Auto Air: Classic Auto Air PN 2-1053 and 2-1054.  These are shown in the catalog pic above. He attached them under his dash using screws through the dash top. 

I decided to go a different route using the original 240 defrost vents that you'll see below.

<<< Here is my version of the defrost duct.  I trimmed a bunch of plastic off each of the original Volvo defrost ducts and then fitted a PN 0069-4 adapter using some screws.  I added some spare 1/4 inch Dynaliner foam to seal some small gaps. Duct tape would have worked too.  I angled the hose inlet toward the incoming duct hose, so the duct hose fit nicely.

<<< There's a screw covered by my thumb in this pic. Sorry.

<<< All nicely sealed. These were then mounted to the underside of the dash using the original rubber retaining nubbs.  


<<< This is one of the original Volvo dash ducts for the right and left dash end vents.  The square end fits onto the back of the Volvo vent. 

<<< The round end was a bit too large for the 2 inch duct hose, so again, some spare 1/4 inch Dynaliner foam to the rescue.  I stuck some inside the first inch of the Volvo tube.

<<< Pretty nice snug fit now. 


<<< Here is the original Volvo two-vent duct that's found behind the two center dash vents

<<< The two CENTER FRONT outlets on the new AC unit are going to these front center dash vents. They're close together and the original 240 duct spreads them apart before they get to the vents.  

<<< So I ordered this PN 2-2027FA-1 Dual Hose Adapter from Classic Auto Air.  Cost: $20.00.

Then I decided NOT to use it. 

<<< Instead I built this using some parts I had. These parts seemed to fit a little better. 

<<< I began by removing the staples holding the bellows pieces on.  Then I cut open the thin plastic box so the center divider was gone. 

And I trimmed and attached the two duct adapters I had left over so they fit well in the box (Classic Auto Air PN 0069-4).

<<< Here's my new dual hose adapter next to the center vent it will mate with.


Here are the hose ducts beginning to go into place.

This view is through the LEFT SIDE hole for the main gauge cluster. Here's the driver's side defrost vent being held in place using the original rubber nubbs. Fits pretty well.

 And looking through the RIGHT SIDE glove box hole, here's the passenger defrost vent.

And here's the right side dash vent.  The left side looks pretty much the same.

2021 Update:

I think the 2 inch ducts that are designed into the Classic Auto Air units are TOO SMALL.
The longer running ducts, like those going to the far left and right dash end vents, can suffer from the restriction of a long hose.

I discovered that Vintage Air uses 2.5 inch ducts on their units. Good for them. Too bad Classic Air doesn't.
  I had been obsessing over this potential restriction for a while. So I did something about it. 
Math tells us that increasing from 2 inch to 2.5 inch hose increases potential air volume by 56%.
56% increase is not small.
I decided to change all FOUR duct hoses going to the main DASH vents to 2 1/2 inches.  

What I did is simple to explain with this photo above. I bought 8 feet of 2.5 inch duct hose. The above photo will show you the difference between 2 inch and 2.5 inch hose. And the oval shaped duct above is the same size as found on the Classic Air AC unit.
So I added a layer of 1/4 inch foam to each duct outlet on the AC box. This allowed the larger 2.5 inch hose to fit nicely on the outlet. This is not a not perfect solution, since larger duct openings would be better, but this is how this experiment is going.

I bought the above plastic twin duct. It's PN ALL42142 available from Summit Racing or lots of other places. It's actually a 3 inch brake cooling duct.
Those round outlets are sized for 3 inch hose, if placed on the OUTSIDE of the outlets, however it just so happens that a 2.5 inch hose will fit nice and tight on the INSIDE of those outlets.
The 3 inch height is a bit too tall, so I used a heat gun to warm the plastic enough to squish it down so it's would be the same height as the 240 vents. The outlets became ovals, which makes no difference.
Use gloves when doing this, because the plastic will be hot enough to burn you.

After some more heat forming and the use of some tin snips and duct tape, the shape now fits really well to the back of the 240 center vents.


Then I removed the 1/4 inch foam I used before (shown in ABOVE PHOTOS), which I had previously added to the inside of the outer dash original duct.
After removing that foam, the new larger 2.5 inch hose seen BELOW fits PERFECTLY and tightly into the original Volvo duct. 


Assembling New AC Refrigerant Hoses.
Traditional crimping and some alternatives.
Classic Auto Air has a selection of refrigerant hose parts, however their catalog did not have all the fittings I needed.  I ordered the below hose parts from coldhose.com
A parts inventory list with part numbers is listed below CLICK HERE.

C R I M P I N G  
C R I M P I N G   C R I M P I N G
For hose fitting assembly, I already had a hydraulic AC fitting crimper that's used with traditional beadlock AC barrier hose.  This is identical to the original hose used in the 240.
This tool was expensive. I bought it years ago when I first began doing my own AC work.  It can cost $500.

If you decide to use a crimper, now there's a less expensive option for DIY AC mechanics. The Mastercool 71550 manual hose crimper.  It can be mounted to a vise or to a bench. Best of all it's only around $150. 
Or of course you can go to a hose shop and have your hoses custom made. You can expect to pay quite a bit for that service, so buying your own tools makes sense to me if you might be doing this more than once in a lifetime.


Alternatives to Traditional Crimping
There are now some interesting alternatives available that you may want to know about.  These alternatives do not use the crimping methods shown above and do not need expensive tools.


https://www.jegs.com/p/Vintage-Air/Vintage-Air-E-Z-Clip (AKA: Aeroquip EZ Clip) Refrigerant-Hose-End-Fittings/3730164/10002/-1
Video: Assembling Aeroquip E-Z-Clip AC Hose Fittings

Another video explaining the differences between traditional crimps and the E-Z-Clip Hose System.

PDF Instructions: Assembling Aeroquip AC Hose Fittings


All 240s used SAE fittings in their AC systems (with one exception). So this means that if you're repairing or making any hoses for your 240, you'll need fittings with standard or SAE thread, not metric.
The ONE exception: The 1993 (one year only) 240 used an AC accumulator/drier with metric thread.

I used this method for my 240 Installation.

AC hose sizes used in this project:
#6 Hose:  5/16 inch ID,  39/64 inch OD.
#8 Hose:  13/32 inch ID,  45/64 OD.
#10 Hose:  1/2 inch ID, 25/32 OD.

Complete inventory of parts used: CLICK HERE

Here's a new DRIER canister above I installed on the right fender.  It's mounted using a black universal drier bracket. PN DC0002 from ColdHose, $3.00.
The drier is connected using #6 hose fittings on both sides. One is a straight fitting and one is 90 degrees (with a service port).
This 90 degree fitting in this photo above, PN BL1321-3, has the high side service port, which is useful for hooking up to your AC gauge manifold high side hose. 

The hose going from the straight #6 fitting on the drier in this photo above, PN BL1301, goes to the firewall and then to the new AC box. 
All fittings shown used and shown here are aluminum. 
Steel fittings are available if you prefer that.

The hose coming from the front condenser BOTTOM PORT goes to to the above drier. It begins at the condenser with a 90 degree fitting #6 Female PN BL1321 (not pictured). It's nearly identical to the 90 degree fitting in this photo above, except it does not have a service port.  The fitting at the condenser top port is a #8 Female 90 degree O-ring fitting, PN BL1322. The top hose goes to the compressor.

<<< The drier I used is an aftermarket copy identical to a 1980-89 Volvo 240 drier, Volvo PN 1370235.  The one I bought was made by Uro. Cost was about $20.00.  The hose fitting size will be #6 male on both sides.

If possible, you should get a drier that comes with the low-pressure cut-off switch shown on top. If your drier does not come with the switch, then get one that has the port for the switch, so you can re-use an old switch on your new drier. This switch is wired into the AC compressor power circuit and if the pressure drops too low (because you have a leak) the power to the compressor will be interrupted.

This drier also has the over-pressure relief valve on top.  This valve is optional, but it was original on an early 240 driers.  Having one of those is up to you.  I believe most later rotary AC compressors have a built in over-pressure valve on the back. Early (pre-1986) 240 compressors did not have that relief valve. 
There are some aftermarket driers that don't come with either one of these items, so shop wisely if you want them included.

IMPORTANT: The new drier you buy should come with these plastic caps on the inlet/outlet to keep it sealed during storage.  The drier has a desiccant inside, which absorbs moisture to keep that moisture out of your refrigerant.  That desiccant can eventually become saturated with moisture and it will no longer work to remove moisture from your system.  If the drier has been stored without a good seal, then ambient moisture in the air can saturate the desiccant and render it useless. So when you buy a new drier and open it, you should hear a "PHHHHHT" sound of air rushing in when you first open a cap. That will tell you it was sealed correctly in storage.

This is the #6 hose (high pressure side), which comes through the firewall to the new Classic Air AC unit. 
The 90 degree fitting on the RIGHT, PN BL1321, gets crimped to the #6 hose coming from the drier. I made it this way so I could have a quick 90 degree bend at the firewall instead of the typical hose you see coming out over the exhaust manifold and then slowly turning. You can see that below. Barrier hose like this is pretty rigid, so making turns must be a gradual thing, unless you use a fitting.
The straight fitting on the RIGHT, PN BL1801, then goes through the firewall toward the dash.
The 90 degree fitting on the LEFT, PN BL1321, connects to the high-side inlet on the new Classic Auto Air dash unit.

Here's that 90 degree BL1321 fitting I mentioned above going from the high pressure hose, turning and going through the firewall toward the dash.

And here are the hoses coming into the dash area from the firewall and connecting to the new AC unit.  The small #6 hose is the high pressure hose shown above coming from the drier.
The large #8 hose in this photo returns to the compressor. This hose is shown further below in more detail.

This hose above is the large #10 hose seen above coming from the AC unit and through the firewall (to the compressor). 
The 90 degree female fitting on the left, PN BL1323, goes to the AC dash unit. 
The 90 degree female fitting on the right, also PN BL1323, goes through the firewall and then turns left to another #10 hose fitting for the hose going to the compressor.

Here's the 90 degree o-ring fitting, PN BL1323, coming through to the engine side of the firewall.  It connects to a Male INSERT 45 degree o-ring fitting, PN BL1813. before heading toward the compressor. 
Something to keep in mind when trying to figure out how to order fittings: A female o-ring fitting always fits a male INSERT o-ring fitting.

Here it's connected. I chose a 45 degree fitting here because my original plan to have a straight fitting here made the AC hose curve out a bit too close to the valve cover.  That could make removing the valve cover more difficult in the future. 

 This is an in-line splice fitting that I have inserted in the #10 hose going to the compressor.  It has a low-side port for charging. This is a #10 (1/2") Inline Splicer with an R-134a 13mm Suction (low side) Port, PN BL6103-3.

And finally here's the hose that goes from the in-line splice fitting to the compressor. This fitting at the compressor is a #10 Female Straight O-ring Fitting, PN BL1303.

The compressor has two ports. One is larger #10 (in from the dash).
The fitting I used at the compressor is a #10 Female Straight O-ring Fitting, PN BL1303.
The other port is smaller #8 (out to the condenser top port). I used
a #8 Female 90 degree O-ring fitting, PN BL1322.

The fitting at the condenser TOP PORT
(not pictured) for hose coming from the compressor is a #8 Female 90 degree O-ring fitting, PN BL1322. 
The hose coming from the condenser BOTTOM PORT goes to to the drier on the fender. It uses a 90 degree fitting #6 Female
PN BL1321 (not pictured).

Here is an overall view of the #10 hose from the firewall to the compressor. 

Hose Parts Inventory List
This list covers all AC hoses.  All fittings are aluminum.  Below items were ordered from coldhose.com.
BL1321 #6 90 Degree O-ring Fitting Female.  Qty: 2  $7.04 each
BL1321-3 #6 90 Degree O-ring Fitting Female with R-134a 16mm Discharge Port.  Qty: 1 $9.87 each
BL1301 #6 Straight O-ring Fitting Female.  Qty: 1  $3.64 each
BL1801 #6 Straight O-ring Fitting Male Insert.  Qty: 1  $5.74 each
BL1323 #10 90 Degree O-ring Fitting Female.  Qty: 2  $6.22 each
BL1303 #10 Straight O-ring Fitting Female.  Qty: 1  $5.69 each
BL1813 #10 45 Degree O-ring Fitting Male Insert.  Qty: 1  $8.19 each
BL6103-3 #10 (1/2") Inline Hose Splicer w/ R-134a 13mm Suction Port.  Qty: 1  $13.98 each
BH6 #6 (5/16") Barrier A/C Hose Per Foot.  Qty: 8 feet  $2.25 each
BH10 #10 (1/2") Barrier A/C Hose Per Foot.  Qty: 8 feet  $2.75 each
DC0002 Universal Drier Bracket.  Qty: 1  $3.00 each

Not Shown in photos above (hose from Compressor to Condenser)
BL1322 #8 90 Degree O-ring Fitting Female. Qty: 2  $5.89 each
BH8 #8 (13/32") Barrier A/C Hose Per Foot.  Qty: 6 feet  $2.50 each

I began with cleaning up the 240 dash wiring mess.
When you pull the dash (and an original AC box) out of a 240, the spaghetti mess of wires can be overwhelming. In many of these photos you can see pieces of yellow electrical tape with marker writing wrapped around some wires.   As I began this disassembly I took time to mark every wire or connector I found with tape and a description of where it went or where it came from.   It was time consuming, but well worth the effort. Trying to find all those wire locations later without this info would not be very much fun. Also it's helpful to grab your cell phone and snap some photos of this stuff as you go.  That may help out later and you'll have some nice photos to impress your Prius driving friends at parties.

One of the things I did to clean things up was to move the location of the dash relays.  I don't understand why Volvo engineers thought hiding the relays deep inside the dash behind the vents was a good idea.  Now I have placed these relays behind the inner passenger side kick panel.  Some wires needed to be extended on the relay connectors to reach this location.
I used interlocking relay sockets for the relays. There are 6 of them here. Only 5 relays were added here, but there is an extra socket for one more relay if needed.


I added this ground terminal distribution block attached to the side of the lower center storage/radio enclosure. 
This allows me to have one central location for all the dash grounds found in that center dash area.
There is one big fat cable connecting this block to one ring terminal bolted to a convenient dash bolt instead of a bunch of ring terminals connected to different dash bolts all over the dash like Volvo did.

If this is something you're interested in, I have a few extras and I have made them available in my harness parts page here: https://www.prancingmoose.com/blackvinyl.html#terminalblocks.

This is behind my right side passenger kick panel.
My engine management system is here. In order to better organize the wiring you can see here I've added three more distribution blocks:  Labeled 12 Volt Key 1; 12 Volt Key 2; and Ground. 
12V Key 1 has power when the key is it the key first power "ON" position.  12V Key 2 has power in the key second (or "RUN") position. 
There are no covers available for these distribution blocks. I made these cover custom because I wanted some protection for the hot leads.

  I made the covers by forming some inexpensive 1/32 inch gray PVC plastic sheeting I got from McMaster Carr: https://www.mcmaster.com/#8748K21. I then painted them black and added labels.  That PVC sheeting may be formed easily with some heat from a hair drier or heat gun and it's easily trimmed with scissors.  If you try this, make a mock-up cover out of cardboard first so you have a good template.

Buttoning Things Up
<<< Before doing this project, I had a black dash with tan lower parts and a tan center console and kick panels (similar to this random 240 pic. NOT MY CAR).  I decided to change everything in the dash to ALL BLACK.
<<<  No, I didn't paint my tan dash parts black, although that can be done if you prepare them well.  I already had some black parts that I began collecting a few years back.  They were looking a bit old so I cleaned them thoroughly and renewed them with some fresh black paint. I used SEM Color Coat Satin Black.  It has a really nice finish for dash parts. 

<<< Since part of the new AC unit sticks out below the dash into the passenger foot-well, I needed to trim this plastic side kick panel a little. 

<<< Just a little trimming was needed.  Some sheet metal shears worked very well for this.

NOTE: Apparently my setup has the new AC unit mounted a little further from the firewall than Michael's installation.  I found I had some minor glove box interference. The back left corner of the glove box was touching a refrigerant fitting and it was preventing the glove box from going all the way in.  I solved this by trimming a small part off the back left corner of the glove box and then everything fit again. 

Moving the new AC unit closer to the firewall would probably have solved this glove box problem, but for my installation it was not possible because the heater hoses coming through the driver's side firewall near the accelerator pedal interfered and kept the AC unit from being pushed farther forward. Michael Yount's installation was different because his heater hoses came through the firewall on the PASSENGER side (for his Chevy LS motor) and apparently this helped with the new AC box positioning.  Moving m AC box closer to the firewall was not possible unless I moved it more to the right side, away from the heater hoses, but that would have exposed more of the AC box to the passenger foot-well.


Here's the completed result. 

Refrigerant Oil
I used Ester Oil for this system as recommended by Classic Auto Air.  R12 systems typically always used Ester Oil. You may find information online suggesting the use of PAG oil with R134a. Either can be used. Both are synthetic lubricants. The difference is that PAG oil comes in more than one viscosity. Ester Oil comes in only one type.

Charging with Refrigerant

I use a pretty standard R134a gauge manifold set made by Mastercool, which I bought on Amazon years ago. That kit came with pretty cheap service valve couplers, so I later bought a set of the below Robinair 18192 set, which has the dial knob on the back for adjusting the plunger.  I had trouble getting consistent flow through those valves and it seemed like the plunger was restricting flow to a trickle. So then I bought the Robinair 18341 set, which do not have the knob on the back.  Those were a LOT better.  They simply pop on and no messing with an adjusting knob is needed.

Classic Auto Air has some specific instructions for charging their AC systems. 

Place vacuum on the system for 30-45 minutes to eliminate all moisture. Vacuum is best at 28-30 inches Hg.  I used an electric vacuum pump. It's a good investment if you are doing your own AC work. 

Classic Auto Air says R134a is required. Substitutes are not recommended.  I don't always follow rules. You'll see in my observations and results below.

Recommended charge: 24 ounces of R134a.
That's 24 maximum. Do not overcharge.
Classic Auto Air says it's better to slightly undercharge rather than overcharge.

Classic Auto Air says expected low side pressures should be about 15 to 25 PSI.  High side pressure is generally expected to be about 150 to 250 PSI.

  Why do I need to VACUUM the system first?
Air conditioning systems don't like air. Air doesn't harm the system, but it's a lousy refrigerant, so you need to get it out of the system.
Air conditioning systems don't like moisture either. Moisture attacks metal parts and will eventually cause the compressor valves and rings to degrade or fail.
That's the main reason systems sometimes get vacuumed for hours. It's not the air so much as the water vapor that needs to be removed.

I tried to play by the rules.
<<< When I began charging with R134a, I set up a postal scale to accurately measure the charge.  I got 11.8 ounces out of the first can. 

To speed things up, a good trick is to place the can in warm water.  Not too hot.  If it's too hot to touch, it's too hot.  This trick raises the pressure in the can so it flows a little faster.  It took about 15 minutes for the first can.

<<< Some of the water in the bowl turned to ice on can #1.

Here are my pressure readings after emptying can #1. 
R134a  Low: 26 PSI. High: 200 PSI.

Can #2 took about 20 minutes.
Here are the final pressure readings after installing just under 24 ounces of R134a.
R134a  Low: 27 PSI.  High: 270 PSI.

This is something that will ALWAYS be on your mind when putting such a project together.  My system developed a leak somewhere that allowed the refrigerant to leak down in 24 hours. That's a pretty fast leak. It makes you doubt the parts you spent a fortune on, your tools and your sanity.

<<< So I bought a can of R134a with UV dye and a UV flashlight on Amazon. 

Found it!  I could see the UV dye leaking up through the threads on this firewall fitting. 
It turned out to be a cut o-ring, which I did not install correctly. 
One must be more careful when coupling these fitting together. 
Internet sources suggest a bad o-ring causes most leaks in AC systems.

Observations and Results.
I started with 134a.
The air turbine in this new AC unit is smaller than those in original Volvo 240 air boxes.  That was easy to see since the new unit is more compact than the Volvo box. So I expected the airflow on HIGH setting would not be as powerful as the original unit and I was right.  I can't offer a more precise quantification.  If this is a deal breaker for you, then you should keep your original system.

Classic Auto Air specifies to use R134a in their systems.
I've never been much of a fan of R134a.
R134a is not as efficient as the old R12. But I did give it a good try in this conversion and tested it for a number of weeks.

With R134a I was getting IDLE vent temps of 50 degrees Fahrenheit with an ambient temp of 90 degrees.

Running at highway speeds did bring the vent temps down a few degrees to as low as 46 degrees. This did offer semi-reasonable comfort while driving, but it was NOT making me smile. 
I decided I spent too much money to not get a smile out of this!
So I stopped using R134a.

If you're into this AC tech stuff and want to learn about SUPERHEAT and SUBCOOLING (and R134a comparison to Duracool), the below diagrams will help.

versus R134a

I've preferred using Duracool over R134a for a number of years. If you go to their site, you should READ THEIR FAQ SECTION to become more familiar.

Duracool is advertised to be 35% to 40% more efficient than R134a (it's more similar to the efficiency of R12). 
It produces significantly lower head pressures than R134a.
Duracool says that the ideal low pressure readings with compressor running are recommended to be between 28 and 38 PSI (varying depending on the ambient temps).
They recommend that if the low pressure reading is too low, resulting in vent temps that are too cold, another ounce or two of Duracool can be added to bring those up.


Duracool recommends this can to be inverted during charging. This is because Duracool is a mix of more than one component and it will be more evenly distributed by inverting the can and allowing it to be charged as a liquid instead of as a gas.
In MY opinion, if you're going to use this entire 6 ounce can, then charging as a gas is just fine and it'll mix no problem after it's in your car. If you're charging using a large bulk bottle, then it will be more important to always charge inverted as a liquid to avoid depleting the bottle unevenly.
Single component refrigerants, like R12 or R134a (or Propane or Butane by itself), may and should be charged as a gas with the can upright. 

I'm against recommending that anyone charge their AC system as a liquid like this, unless you're experienced enough to avoid damaging your compressor.  If you are NOT experienced, I recommend doing more research or at least use lots of CAUTION. This is because if you don't use caution, you may inject an UN-compressible liquid into your running compressor, which has the potential to destroy it instantly. Feeding liquid refrigerant into a running system should, at the very least, be done very slowly.

If you have pulled a vacuum on your system because it was opened to the atmosphere for repair, Duracool recommends that a liquid charge to the suction (low) side of the compressor should occur initially with the compressor off. Then one should wait about 30 minutes for the liquid to boil off to a gaseous state and then move on to the next step of adding more with the compressor on. The use of an AC gauge manifold set helps greatly to regulate the whole process and permit the system to be charged in a more precise and controlled manner.

Pressures readings for my installation after initial charge: 
DURACOOL: 25-28 PSI low,  125 PSI high.

As mentioned, Classic Auto Air recommended 24 ounces of R134a for this conversion. 
The Duracool equivalent is about 10 ounces.
A 1986 240, which uses about 2.9 lbs of R12, should only need about 16 ounces of Duracool.
A 1993 240, which uses about 1.63 lbs of R134, should only need about 11 ounces of Duracool.  

Here's a table below showing precise conversions
(from the Duracool website FAQ section).

A bit more info about Duracool that I have compiled.
Duracool can be purchased in any quantity without a fluorocarbon HVAC license (so can R134a, except in large canisters).
Since Duracool is a hydrocarbon and not a fluorocarbon, it is 100% compatible with all lubricants used in R12 and R134a systems. All lubricants
. It's also compatible with all elastomers used in refrigeration O-ring seals, hose linings, etc.

 Duracool is non-toxic (as opposed to R134a), it does not negatively affect the environment or ozone (as opposed to R134a), and it doesn't produce deadly phospene gas if exposed to a flame (as opposed to R134a). 

Duracool isn't illegal to buy or to put in your car (some people think it is and Dupont would like it to be). It's just hard to find an AC shop who will install Duracool or do any work on a car with Duracool.  This is partly because most AC technicians have paid good money for their fluorocarbon licenses and they want to keep the business as proprietary as they can. Also they consider anything but the standard Dupont designed refrigerants to be "contaminants" to their pristine equipment if they hook up to your Duracool infected car. 
For these reasons, Duracool servicing may make more sense for do-it-yourself AC work only.

There are people who actually consider themselves to be intelligent who will be promptly tell you your car will explode in a ball of flames if you use a hydrocarbon refrigerant. They forget that they are driving around with 15 to 20 gallons of highly volatile gasoline, which is pumped through hoses under high pressure. And they worry about a few ounces of hydrocarbon gas.  I hope these people never move into a house using propane or natural gas.

If you read the MSDS information for R134a, you will find something like this: "R-134A is not flammable at ambient temperatures and atmospheric pressure, however, this material will become combustible when mixed with air under pressure and exposed to strong ignition sources."  R134a is not as harmless as you might have been told.

I did some reading and found information about a common characteristic of refrigerants called LATENT HEAT. This involves the evaporation potential of a refrigerant in the refrigeration cycle, which is the reaction that produces cooling in your evaporator. The LATENT HEAT value of a refrigerant should be high for the best cooling potential in an evaporative system. And the weight (or MASS) of the refrigerant will be less for any refrigerant with a higher latent heat. Less mass reduces the need for a larger system, meaning a smaller system can be just as efficient with a high LATENT HEAT refrigerant .

The below LATENT HEAT CHART is from a US Department of Energy study in 2006 on the potential of different refrigerants for cooling power electronics in EVs and hybrids. It specifically compares CFC-12 and HFC-134a to replacements, like Duracool, Enviro-Safe (ES-12) and Freeze 12, among others. It can be found at the following link. https://info.ornl.gov/sites/publicat...s/Pub57507.pdf. This document describes LATENT HEAT as the amount of heat unit per mass required to convert the refrigerant from a liquid to a vapor state. Ultimately, this means that a refrigerant with a larger LATENT HEAT VALUE can remove more heat.

Chart for comparison below. ES-12 is Enviro-Safe. CFC-12 is R12.

Since we know that Duracool is a mixture of Propane (R290) and Butane (R600), we can further compare the latent heat of evaporation of these chemicals, as long as you're still comparing by the same quantity (kJ/kg).
  Propane (R290): about 428.
Butane (R600): about 385.

Here an information video from Duracool. (3:41 length)

Duracool is more efficient that R134a and in my system, it gets considerably colder.
This testing was done at idle and on the road.

The first Duracool tests were done at end of summer 2017. With Duracool (while idling) I saw a low vent temperature of 27 Fahrenheit with an ambient temperature of 80
F. That ambient temp was not very high, but by this time cooler fall temperatures were coming.  This vent temperature was recorded at idle in my garage with the fan on the lowest setting.  As the AC continued to cycle on and off, the vent temperature ranged between 27 and 32 F.  Increasing the fan speed tends to bring the vent temperature up several degrees because more warm air is being pushed through the evaporator. 

When summer 2018 came along, I did more testing with high ambient temperatures of more than 100 F.  After initial start-up in my garage, vent temperature at idle was 46 F.  Since 46 F felt pretty good with that kind of outside temperature, I was curious about my wife's new Subaru Forester. So I tested the Subaru AT IDLE with the same 100 F plus outside temperature.  It recorded a vent temperature of 43 F.  My 240 wasn't too far behind that.

While road testing at 55 mph with an ambient outside temp of over 100 F, I have recorded low vent temps of 25
F (PHOTO BELOW) however more common vent temps seemed to be around 31-32 F.
Yes, I will agree with you that allowing the temp to dip below freezing can introduce problems. See the below section on preventing FREEZE-UPS.

So it appears my potential vent temperature drop below ambient is around 53
-55 F at idle and around 68-74 F degrees at 55 mph.  This is awesome cooling compared to before! 
Yes, this kind of performance makes me smile.
  CAUTION: 25 degrees is too low.
Any temps below freezing can have a potential negative affect. You should read the BELOW section on preventing freeze-ups and how I manage this.

I discussed freeze-ups briefly in a previous section, but I'll go over this subject in more detail here, including how to prevent it.
There can be TWO different types of freeze-ups in an auto AC system.

FREEZE UP type 1.
This occurs when moisture in the air on the OUTSIDE of the evaporator turns to ice. This can happen when the outer surface of the evaporator drops below freezing and begins freezing the condensation moisture collecting on it. Small amounts of frost on your evaporator will not cause problems and when the frost or ice melts, it'll drain out to the bottom of the car. If the evaporator gets or stays cold enough for a long enough time, ice can continue forming much heavier. If enough ice forms over time, it can eventually block the flow of air going through the small evaporator coil spaces. This blockage will result in poor airflow through the vents and any air coming through may not be as cold as it should be.

Since you probably can't climb under your dash to look for ice on your evaporator, there are other ways to detect ice. A sign of ice forming can be found under your hood on your AC suction hose (low pressure hose).  This image below isn't a Volvo, but it shows what you can find.  This is frost accumulating on the pipe or hose coming from the firewall. This hose goes to the compressor or to the accumulator on a later 240. This is the return (suction) line for refrigerant returning from the evaporator to the compressor.
Ice forming on this line means things are usually too cold. Most often you won't see ice like this on a normal working AC system, but instead you'll see light frost or cold beads of water condensation.

Freeze up conditions are temporary and will not damage the system. It will, however, damage your sanity.
FREEZE UP type 2.
Another type of freeze-up can occur if there are traces of moisture INSIDE your system.  If your evaporator dips below freezing (32 Fahrenheit) and if there are any traces of moisture in your refrigerant, that moisture can crystallize (FREEZE) as it enters the evaporator coil. If enough ice forms at the coil entrance, it can temporarily block the flow of refrigerant.  If this occurs, then the first symptom will be the AC vents expelling ambient temperature air.

If you were to connect a pressure gauge manifold to your system when this is happening, you would see reduced pressure in your low pressure side (the line between the evaporator and compressor).  This reduced pressure can even become a vacuum if the blockage in your evaporator is severe enough. If this occurs, there's not much you can do except turn it off and wait for it to thaw out, which can take hours. This INTERNAL freeze-up can be prevented or reduced by thoroughly vacuuming your system to remove air (and moisture) before charging it with refrigerant. Also replacing the receiver/drier canister will be a good idea if you suspect that an internal freeze-up has occurred, or if the drier canister hasn't been replaced in a long time (or ever), especially if the system has been opened or serviced and it wasn't replaced during that service. The drier canister contains a desiccant for moisture removal.
A new
drier canister is not expensive and replacing it should be a matter of maintenance when the system is worked on. 

Years ago when I was experimenting with PROPANE in my original Volvo AC system (CLICK HERE), I was able to get very, very cold AC at times, but I eventually gave up on propane because performance was too inconsistent. Considering that experience now, I think the problems I experienced might have been because of internal freeze-ups, since at one time I recall I getting under the dash with my laser temp reader and I measured the evaporator at 17 Fahrenheit.
Who knows? If I had found the below temperature controller back then (if it existed yet), my experiments with propane might have been a success.

RECEIVER/DRIER Canister: An old receiver/drier can become useless if the desiccant inside becomes saturated with moisture. This can easily happen if the system was ever left open or it the receiver/drier was sitting on a shelf for a long time and the seals weren't 100% air-tight. If you remove the sealing CAPS on a new receiver/drier and you don't hear the "PSSSSST" of rushing air, then it was not properly sealed.

So maybe you're thinking that YOUR AC system isn't getting anywhere near cold enough to freeze. This might be true, but keep in mind that vent temps can be higher than your evaporator exterior temps. So even if you might not be concerned about freeze-ups, there are ways to improve things.  Keep in mind that my current Classic Auto Air system was designed to use R134a and I did use that at first, but after I got disappointing results, I switched to Duracool R12 replacement and that got the temperature down substantially. 

Injecting some higher tech into old school AC control.
2020-2022 Updates

Here's a new device I've been using for a while to control my evaporator temps and prevent it from getting TOO COLD.

This is the BAYITE TCF-3A035 12V DC Digital Temperature Controller (in Fahrenheit) with internal 10A Relay and Sensor.
It can be found here: https://www.amazon.com/gp/product/B011VGAPOC/. Cost: $18.00.
There are nearly identical controllers out there from different sellers, but some versions use 110v AC, so avoid one of those if being used in a car. You can search "12 Volt DC Digital Temperature Controller" and you'll find them.

Why would I need to better control my evaporator temperature?
I'm using this device to monitor the temperature of my evaporator outlet pipe and to allow me to see the evaporator temperature. Before using this I found that my evaporator was been getting considerably colder than 32 Fahrenheit at times.The main reason for this is because I'm using Duracool, which is considerably more efficient than R134a, which the Classic Air AC system was designed and calibrated for.  

The programming functions for this unit allow me to program it to cut power to the AC compressor if my evaporator becomes too cold.

I have the sensor tip taped to the outside of my evaporator outlet pipe under my dash. I then insulated it with some foam tape.
The evaporator outlet pipe is the one that goes to the low pressure hose that returns refrigerant from the evaporator unit to the compressor.  
This device is small, about 3 inches wide.
Programming it was not difficult once you read and re-read and then absorb what the instructions are telling you.
For this type of programming you would use COOLING MODE, which I have circled on the second image below of the CONTROLLER INSTRUCTIONS.

When I want maximum cold AC, which is usually what I use, I can set the programming to allow the AC compressor to run normally until the evaporator dips to 32 Fahrenheit. It then CUTS the compressor power and remains OFF until the temperature rises one degree to 34
This OFF-ON gap can be one degree like I set it for or any custom setting you like.
This device does an excellent job of regulating temps and I have not experienced a suspected freeze-up since I began using it.

Here's a video I made below showing how this controller regulates the AC temperature. 
NOTE: That on/off switch on the right side is not part of the controller. I added that to switch off the controller power if needed. I thought that might come in handy, but so far I've never needed to switch it off.


Here's a simple wiring diagram I made for my use of this device. This controller simply INTERRUPTS or CONNECTS the ground circuit for the relay I'm using to turn on the AC compressor.
Can you use a device like this with any normal factory Volvo AC system? 


If you somehow manage to get your normal AC to get super cold and you're concerned about it getting TOO COLD, this device would work just fine.
I know that some Volvo AC systems, such as the later ORIFICE TUBE systems, are capable of getting super cold, especially if you use a hydro-carbon refrigerant, such as Duracool.

QUESTION: Can I adjust the set temperature on this unit while driving without having to push a bunch of buttons to enter a programming mode?
YES you can.

Simply press the SET button. The set temperature will display. Then press the UP or DOWN button to change it.  Then leave it and the unit will change back to default display in about 5 seconds.  Your new SET TEMPERATURE has been changed.
The RED LAMP next to "WORK" is letting you know the controller has switch ON your AC. When that lamp turns off, the controller has switched it off.

Here's a video I made below showing how the SET TEMPERATURE is quickly changed if needed while the AC is running.

If you have questions or decide to try one of these with your AC, let me know how it works for you. Send me an email.


Here are images below of the instructions and programming guide. I circled the area in orange that I used for setting the cooling programming on mine.

A downloadable or printable PDF of these instructions is here: https://www.davebarton.com/pdf/BayiteTCF3A035TempController.pdf

Update: May 2023

I've been using this system along with the above added TEMP CONTROLLER above for three years. This includes thousands of miles or driving with a number of trips across the entire country. So far it seems to work really well.

During road tests with outside temps of 100 degrees PLUS Fahrenheit, my AC vent temps have been consistently at mid to low 30s Fahrenheit at highway speeds.
Before, WITHOUT THIS TEMP CONTROLLER, my evaporator would definitely dip well below freezing
(because that can happen with Duracool). So this device has been very successful at stabilizing temperatures to prevent freeze-ups.

If you've done an AC upgrade to your Volvo and you can share it or if you're thinking of doing something like this, please email me.  I'd like to hear all about it.  
Also, if you have any questions or suggestions to improve the information in this page, please let me know.  Thanks, Dave


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