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
VOLVO 240 AC PAGE
And Classic Auto Air AC Installation Project


     UPDATED: September 6, 2021                       CONTACT       
D  O  M  A  I  N  S
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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

CONTACT  ME

CONTENTS
240 AC INTRO
Later 240 AC
240 AC Systems Overview
Later AC Wiring Diagram
PROPANE AC
DURACOOL 12
First Classic Auto Air
Installation (2016)
Dave's Classic Auto Air
Installation (2017)
Classic Air vs Vintage Air

Dash Wiring Clean-up

134A vs Duracool RESULTS
Preventing FREEZE-UPS
Evap Temp Controller



AC INTRODUCTION
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 for a high result.  The 1984 Volvo 240 factory specifications called for AC output temperature from the center vents to be 48-54 degrees Fahrenheit.
The AC was improved in 1991 when a different system was designed.
 

Image below shows a pre-1991 240 AC, showing small AC drier on passenger (right) fender.

 


So then later 240 AC is better?
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 1990 and 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 refrigerant.

Evaporator Coil Design Changes.
The 1991 and later 240 evaporator box under the dash was a different design for 1991-93 and it used a more efficient evaporator coil. 
The first photo below shows the old TUBE AND FIN design.  The second photo is the more efficient and larger 1991-93 design.


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.

Image below of 1991-93 240 AC (showing large accumulator/drier near firewall).


Here's a photo of a 240 ORIFICE TUBE being removed. This is from the following thread on converting a 240 AC to a later system: https://forums.turbobricks.com/showthread.php?t=357795.
An orifice tube is a restrictive valve that is meant to make the pressurized refrigerant expand after it passes. It is generally made up of a metal tube with a chamfered inlet, a plastic tube body
An orifice tube can become clogged if any contaminates get into the system or in the case of a compressor failure. In this case the tube should be replaced.


USEFUL 240 AC PART NUMBERS
1395590, 3513066 Compressor 240 to up 1992 R12.
3540789 Compressor 240 1993 R134a.
1370235 Accumulator/Drier 240 1990 R12 (RHD, LHD).
1388667 Accumulator 240 1991-92 R12 (LHD).
3540009 Accumulator 240 1991-92 R12 (RHD).
3537542 Accumulator 240 1993 R134a (LHD).
3540588 Accumulator 240 1993 R134a (RHD).
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).
3540227 Condenser Fan Pressure Sensor/Switch 1991 R12.
6848106 Condenser Fan Pressure Sensor/Switch 1992 R12.
3540657 Condenser Fan Pressure Sensor/Switch 1993 R134a.

Can I convert my old 240 to have 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:
https://forums.turbobricks.com/showthread.php?t=322912
https://forums.turbobricks.com/showthread.php?t=330298
http://forums.turbobricks.com/showthread.php?t=355505

 CLICK HERE to see a comprehensive WIRING DIAGRAM for later 240 AC >BELOW<.




240 AC Systems
General Overview Information

If you want to learn more about 240 AC systems, then this information will help.
SAE or METRIC 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 new hoses, you'll need fittings with standard or SAE thread, not metric.
There is ONE exception.  The 1993 (one year only) 240 reportedly used an accumulator/drier with metric thread 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. 

NOTE:
  The "Standard Unit" or "Standard Heater" was an AC delete system 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 R12a refrigerant with a Thermal Expansion Valve (TXV) to control and release pressurized refrigerant into the under-dash evaporator.


<<< (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 (using orifice tubes) 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.
I created the below diagram because nothing like it exists anywhere in any Volvo Greenbook and so many people needed to know where all those vacuum hoses go.

For more vacuum diagrams, go to my Vacuum Diagram Page
 

I get a lot of questions about LATER 240 systems like this.
I don't have all the answers, but I know one of the most misunderstood things are the pressure switches (sensors). 

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

1. One pressure switch is mounted in the accumulator/drier. It's a low pressure switch (or pressostat) that is designed to read internal refrigerant pressure in the evaporator (which immediately follows the accumulator).  This switch controls compressor cycling and is designed to cut power to the compressor clutch when pressure in the evaporator drops below 23.2 PSI (for the R134a switch) or below 26.1 PSI (for the R12 switch).  It then allows the compressor to come back on when pressure in the evaporator exceeds 44.9 PSI (for the R134a switch) or exceeds 46.4 PSI (for the R12 switch). 

It does this because when pressure in the evaporator drops below 23 PSI, the evaporator can get cold enough to freeze the coils and any moisture or humidity on the outside of the coils will begin to 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 with your refrigerant.  There shouldn't be any, but if the system is opened, then air can enter and air contains moisture. This is a good 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 and 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 fan OFF when it drops below 188 psi.
3540227 Condenser Fan Pressure Sensor/Switch 1991 R12.
6848106
Condenser Fan Pressure Sensor/Switch 1992 R12.
3540657
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 that guards against over-pressure situations.  These systems all use a mechanical pressure relief valve on the compressor 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). 

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 (evaporator outflow or suction pipe). For 1991-92, this valve will be configured for R12.  An adapter fitting may be used to convert it for R134a filling.
For 1993 models, this fitting will be configured for R134a.



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 is common to find NO HIGH PRESSURE SERVICE VALVE.




Here's a comprehensive WIRING DIAGRAM I created for the 1991-93 240 AC system (Orifice Tube type). 
CLICK BELOW IMAGE for 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



CFC R12 Refrigerant
R12 refrigerant was used in all 240s through 1992. As previously mentioned it was later banned in the U.S. and other developed countries in 1996 and worldwide in 2010. 

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 and then later TXV cars using R134a had valves that were set or adjusted differently.  This raises the question about DIY users doing their own adjustments on TVXs to suit R12, R134a or a suitable substitute refrigerant.

The adjustment method on a TXV used in a Volvo is illustrated below.
An Allen wrench is inserted into the inlet port and there's a set screw that is turned.  There are many opinions on what these adjustments need to be for different refrigerants and so far none of it is very definitive.
A discussion thread on setting these valves is posted below.
 TXV Adjusting thread:
https://www.forums.turbobricks.com/showthread.php?t=213526



USING PROPANE AS A REFRIGERANT.
Over the years I have done a lot of experiments on my 1984 242 AC. Some have responded fairly well, but none would seem to work like a real modern AC system is supposed to.
Beginning in 2010 I made a serious attempt at using PROPANE as a refrigerant after a suggestion by another 240 owner I knew who claimed to be successful. 

Propane is a fuel that is produced in the crude oil refining process. It's made up of 18% Hydrogen and about 82% Carbon. This is why it's call a Hydro-Carbon (HC).

I built this service hose below, which had a fitting for a small 1 lb. propane bottle. The small fitting is an R12 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.
A 1 lb. propane bottle will typically have a maximum pressure of 120 PSI when full.



My success with propane 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 certainly may have contributed to suspected freeze-ups and the intermittent failures, but I could never confirm it.

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

One occurs when trace moisture in the 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 will not cause problems. 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 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. 

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. If enough ice forms, it will temporarily block the flow of refrigerant.  If this occurs, then a symptom will be less or no cool air from your vents. Another symptom would be reduced pressure in your low pressure side line (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 concept is something my self-taught amateur understanding did not consider years ago during those propane experiments years ago. I suppose it's also possible there could also have been some moisture in the propane I was buying.  Propane is not made for AC systems, so I suppose it's possible the refining standards might not remove all moisture, like for actual refrigerant.

MORE INFO ABOUT FREEZE-UPS AND HOW TO SOLVE THEM IS INCLUDED IN THE
FREEZE-UP Section HERE.


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. 

There is an extensive Turbobricks thread here if you want to see more on adventures with propane:
https://forums.turbobricks.com/showthread.php?t=202992



DURACOOL (Hydro-Carbon Refrigerant)
In 2012 gave up on propane and moved to Duracool R12a replacement http://www.duracool.com/ Duracool is a mixture of Propane and Butane. It seemed to be a little more consistent than propane. During this time I tried a number of different thermal expansion valves and a LARGE number of different expansion valve settings. My 240 got pretty good cooling on the highway, but I still found problems at idle (although it seemed a little better). I kept experimenting over the years with many different expansion valves and a huge variety of different adjustment settings on those valves, hoping to find a combination that worked.  Things never got much better and ultimately I remained less than fully satisfied with my AC.
CLICK HERE TO SEE MUCH MORE ABOUT DURACOOL AND MY ULTIMATE RESULTS.

Reputations of Aftermarket AC Systems
Over the years, whenever I would come across custom hot rods at car shows with custom retrofitted AC systems from Classic Auto Air or Vintage Air, I became 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 looking 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 past skepticism tended to pollute any confidence I might develop in aftermarket AC systems.

The answers I got, however, from every one of those hot rod owners about their Classic Auto Air or Vintage Air systems were very positive.

So after Michael Yount successfully installed his system in his 240 (below), I paid attention and started seriously re-considering.


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

CONTACT  ME




CLASSIC AUTO AIR in a 240.
First came Michael Yount's 240 Installation.

This is what began my conversion 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.

His car has been featured in my Favorite 240 Page: https://www.240turbo.com/volvo240.html

Michael reported exceptional results with 36 degree vent temps at idle on 90 degree highly humid days. 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 stayed in Volvo AC hell. 


Here are a few pics Michael sent me showing some details of his installation:
This AC box is the Street Rod Cooler III from Classic Auto Air.  The shape of the aftermarket AC box is very different from the original 240 AC 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 AC box in the car just under the windshield cowl. 
 

Classic Auto Air has several versions and sizes of AC boxes. This is one of their all electronic boxes.  An electronic box like this one eliminates the cable and vacuum controls originally found in a 240.  So this means your 240 vents and temp controls are done electronically and all those original vacuum buttons and cable controls go away. 

 With the old airbox area gutted, here's a view of Michael's car with the new AC box sitting under the dash.  The design of this Classic Auto Air box is more compact than the original Volvo box, however it's much WIDER than the original Volvo box.

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


There are some compromises or TRADE-OFFS with this system.
As you can see in these pics, the new AC box is a bit wider than an original 240 box, so part of it can be seen extending into the passenger footwell, so that kick panel needed a little trimming. This is a small trade-off that I was be willing to accept. 


The width of the Street Rod Cooler III unit is 20.875 inches (full dimensions found HERE). 
Michael reported that his installation did not require any modification of the dash or glove box, except for some trimming on passenger the kick panel.
Classic Auto Air also has one larger AC unit (named the "Custom Colder") that 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 trade-off: 
This system will NOT accommodate the original FRESH AIR VENT below the cowl, at 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 using this system, you'll need to open your lower kick-panel vent or crack a window.  That original fresh air hole under the cowl will need to be closed off and sealed to keep the weather out of your car. 


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 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 to see the 240 DYNAMAT Installation

  If you have any suggestions to improve the information in this page, please email.  Thanks, Dave

CONTACT  ME



Classic Auto Air Installation
in my 240 (2017)

Introduction of 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.
Dimensions: 
Width: 20.875 inches
Height: 9.5 inches tall
 Depth: 7.125 inches.
Update NOTE : Considering the price increase noted above, you might also explore VINTAGE AIR. When I began this project, there was NOT very much detailed info available about the differences between the two systems. One difference I'm now aware of in VINTAGE AIR systems is larger dash duct outlets on the unit: Vintage Air uses 2.5 inch ducts instead of 2 inches in Classic Air outlets. I don't know how much of a difference this makes, but I suspect it does help with air flow.

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



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 diagram above came from).  They have a link to PDF file downloads at the bottom of their web page. 

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

NOTE ABOUT
HEATER AIR DUMPS

The Heater Air Dumps shown in the illustration above and below 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 hoses.

NOTE: Before installation I moved these DUMPS to the two INSIDE duct outlets so that the duct hoses going to my defrost vents would be on the outer ducts. This provides more room for the flexible duct hoses.


There were not many photos of this unit in their 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.



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 also if you need one.  I didn't buy one from them though.

<<< An early 240 like my 1984 originally came with a York compressor like this one, which came in 240 models before 1985. 

<<< A newer rotary style compressor is better, quieter and more efficient. This style was originally equipped in 240s beginning in 1985. My 1984 240 had been changed to a new rotary style compressor back in 2002 by the previous owner. That compressor was a little noisy after 15 years, so for this project I purchased a new rotary compressor from FCP Euro:  Volvo PN 8251069 (click here).



 I had already installed an oversized (16 x 24 inches) parallel flow condenser a number of years ago. You can buy one from Classic Auto Air or Coldhose. They come in many different sizes. 
If you're wondering what a Parallel Flow Condenser is, it's basically a newer and better design than the original style condensers our 240s came with. They are reported to be about 30% more efficient than the old type my car came with.
 

I also installed dual 11 inch pusher fans mounted to this condenser.  A pusher fan is recommended to get better air flow when you're stopped or at low speeds.



Mounting the new Classic AC Box
 Note that the unit is inverted in this photo below.
 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 AC box comes with some mounting points with U-nuts 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) more, because they'll interfere with the accelerator pedal..

The kit came with some clear drain tube for the condensation drain on the bottom, 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. They came 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 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.

  

The below photo is of the underside of the cowl just below the center of the windshield.  This is where the fresh air 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, which would be bad.
 
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 that used to hold the top of the factory heater/AC box.  As Michael did, I used those brackets as top mounts to help secure the new AC box.


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


Here's an illustration of how this unit fits in my car.


It's hard to see here (BELOW PHOTO), but the brackets I made which are attached to the backside of the AC unit, now reach up to the original top cowl sheet metal brackets.  I also bolted in a small steel bracket to the transmission hump below the new AC unit for a lower mounting point. It can be seen in a different photo further below. That bolt hole was one of the lower mounting points for the original AC box. At all mounting points I used zipties to secure the new AC unit.  It's mounted very firmly and all of the vent duct outlets have adequate clearance from obstructions. 


This photo is looking down at the 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 top cowl mounting points. I've zip-tied them to the new AC box brackets I made.  UPDATE: You should notice that I made a last minute change and moved the HEATER AIR DUMPS from the OUTER rear air outlets to the INNER REAR OUTLETS, so now they are right next to each other.  This was a suggestion by Michael Yount. It helped to provide more clearance for defrost duct hoses on the rear 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 upper or lower vents are selected, so 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.

 

Alternate LARGER AC UNIT INFO
As mentioned above, the Street Rod Cooler III unit I bought will not control the upper defrost and lower heater ducts independently. If you think you really must have the top defrost and bottom heat vents controlled independently, there's a larger AC unit from Classic Auto Air called the "CUSTOM COLDER" unit, shown BELOW.  It's their largest unit and it will do these vents independently.
As mentioned earlier, this larger unit is 24 inches wide, 10 inches tall and 8.75 inches deep. That comes to 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 could see under the dash in the passenger foot well. It's 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.

"CUSTOM COLDER" from Classic Auto Air
 

Here's an approximate illustration of how I think this unit should fit.



Comparable VINTAGE AIR unit.
VINTAGE AIR makes a comparable unit that you may want to consider also. When I began this project, there was very little much detailed info available about the difference s between Classic Auto Air and Vintage Air. Classic Auto Air advertises that they have larger evaporator coils. Another difference I'm aware of in VINTAGE AIR systems is they have LARGER dash duct outlets on their units: 2.5 inches instead of 2 inches in Classic Air dash vent outlets. I don't know how much of a difference this makes, but I suspect it would noticeably help with airflow. 

Here's a useful comparison of units from both companies you can read: https://www.digitalcorvettes.com/threads/classic-air-or-vintage-air-here-are-my-findings.272233/

As of May 2021 this Gen II Super (Heat, Cool and Defrost) from Vintage Air was priced at $510.00.
This unit is about 3 inches wider than the unit I used.  Dimensions: 24 inches wide x 8.5 inches tall x 8.5 inches deep.
https://www.vintageair.com/builder-series/Gen2Super




Here's an approximate illustration of how I think this unit should fit.




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).
Would another 3 inches of airbox width under there be too much??? Probably not.


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. 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.



240 HEATER HOSE ORIENTATION
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 that begins behind the engine and goes to the back of the water pump.

ELECTRONIC WATER VALVE ORIENTATION
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 FLOW direction in this photo is from RIGHT to LEFT. This valve is installed in the RETURN LINE that goes from the AC box to the BOTTOM HOSE at the firewall, which returns coolant to the water pump. The following link has instructions for a different AC box than I used, but it has the correct instructions for this valve: https://www.classicautoair.com/manuals/1-1081Manual.pdf

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 to the water pump suction/return.
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.
 



VENT DUCT WORKINGS
The duct outlets on this new Classic Auto Air unit are designed for 2 inch flexible tubing.  They sent me 15 feet of their tubing with my kit (like the image BELOW). The tubing fits 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 ducts going to the rear floor behind the front seats
(going under the carpet and under the front seats) were removed when I was applying Dynamat. Those are not needed and are 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.  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 verson 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 Dynaliner foam to seal some small gaps. 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 nubbs.  



 

<<< This is one of the original Volvo dash ducts for the right and left 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, Dynaliner foam to the rescue.  I stuck some inside the first inch of the Volvo tube.

<<< Look at that!  Nice snug fit. 

 

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

<<< The two center outlets on the new AC unit are going to these front center dash vents. They're close together and the original 240 adapter spreads them far apart.  Not the best match. 



<<< So I ordered 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 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.



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



 And looking through the 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.
 

Assembling New AC Hoses
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 part 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.  It's an expensive tool I bought years ago when I began doing my own AC work.  It can cost over $500.
Since there is now a less expensive option for DIY AC mechanics, I recommend the Mastercool 71550 manual hose crimper if you decide crimping is for you.  It can be mounted to a vise or a bench and best of all it's only around $150. 
Or you can go to a hose shop and have your hoses custom made. You can expect to pay quite a bit, so buying your own tools makes sense to me if you might be doing this more than once in a lifetime.

https://www.youtube.com/watch?v=DHAHa9_UWQU



Alternatives for Building AC Hoses without Difficult Crimps
There are 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 any expensive tools.
https://www.forums.turbobricks.com/showthread.php?p=5862424

http://www.atcoproductsinc.com/products/air-o-crimp

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

https://www.jegs.com/p/Aeroquip/Aeroquip-Air-Conditioning-Hoses-And-Hose-End-Fittings/753042/10002/-1
http://aeroquipperformance.com/c-1011477-fittings-a-c-fittings-a-c-refrigerant-hose-fitting.html
PDF Instructions: Assembling Aeroquip AC Hose Fittings


SAE or METRIC 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, you'll need fittings with standard or SAE thread, not metric.
There is ONE exception.  The 1993 (one year only) 240 used an AC accumulator/drier with metric thread.



Traditional Crimp AC Hoses used for my Installation

Complete inventory of parts used CLICK HERE


Here's a new DRIER canister 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 shown in the photo. One is straight and one is 90 degrees.

The hose coming from the condenser to this drier begins at the condenser with a 90 degree fitting (not shown). It's identical to the 90 degree fitting in this photo, except it does not have a high side discharge port. This 90 degree fitting in this photo has the high side discharge 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 goes to the firewall and then to the new AC box.  All fittings shown are aluminum.  Steel fittings are available if you prefer that.

<<< The drier I used is an aftermarket copy that is identical to a 1980-89 Volvo 240 drier, Volvo PN 1370235.  The one I bought was made by Uro. Cost is about $20.00. 

You should get a drier that comes with the low-pressure cut-off switch shown on top. 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, (closer to the fender in the above photo).  This valve is optional, but it was original on an early 240.  Having one of those is up to you.  I believe most later rotary AC compressors have a built in over-pressure valve. Early 240 compressors did not have that.  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 caps on the inlet/outlet to keep it sealed during storage.  The drier has a desiccant inside, which absorbs moisture to keep it out of your refrigerant.  A drier can eventually become saturated with moisture and it will no longer work to remove moisture from your system.  If the drier is or has been stored without a good seal, then ambient moisture can saturate the desiccant and render it useless.


This is the #6 hose coming through the firewall to the new Classic Air AC unit.  The 90 degree fitting on the right 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 coming out over the exhaust manifold and then turning. The 90 degree fitting on the left side connects to the high-side inlet on the new Classic Auto Air unit.


Here's that 90 degree fitting I mentioned above turning and going through the firewall.


And here are the hoses coming into the dash from the firewall  and connecting to the new AC unit behind the dash.  The small hose is the same as the one shown above. It's the high pressure hose coming from the condenser and drier on the right fender.

The large hose in this photo returns to the compressor. This hose is shown further below in more detail.


This is the large #10 hose seen above coming from the AC unit through the firewall to the compressor. 

The 90 degree female fitting on the left side goes to the AC unit. 

The 90 degree female fitting on the right side goes through the firewall and then turns left to the #10 hose going to the compressor.

Here's the 90 degree o-ring fitting coming through the firewall.  It connects to a Male Insert o-ring fitting 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 for that male insert o-ring fitting.  I did that because my original plan to have a straight fitting there made the AC hose a bit too close to the valve cover.  That could make removing the valve cover more difficult. 


 This is a 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 splice fitting to the compressor. This fitting is a #10 Female Straight O-ring Fitting, PN BL1303.

I did NOT discuss the hose from the compressor to the condenser, which can also be seen here. 
This is because I used the existing hose I installed back when I installed that new condenser.  It's constructed using the following:  #8 Female 90 degree O-ring fitting, PN BL1322 at the compressor.  Then a length of #8 barrier hose, PN BH8.  Then at the condenser there is another
#8 Female 90 degree O-ring fitting, PN BL1322.



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



Hose Parts Inventory
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




Cleaning Up the Dash Wiring
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. There are 6 of them here. Only 5 relays for now, but there is an extra socket for one more relay if needed. These interlocking relay sockets are available in my page here if you need to see them close-up: https://www.prancingmoose.com/blackvinyl.html#relayplugs



TERMINAL BLOCKS
<<<  I added this ground terminal distribution block attached to the side of the 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 the right side, below dash area, behind the right 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:  12 Volt Key 1, 12 Volt Key 2 and Ground.  12V Key 1 has power when the key is it the first power "ON" position.  12V Key 2 has power in the second (or "RUN") position.  The covers for the distribution blocks are not available. I made them custom because I wanted some protection for the hot leads.

I made the covers by forming some 1/32 inch gray PVC plastic sheet 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 is easily trimmed with scissors.  If you try this, make a 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.  I already had some black parts 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's a really nice finish for dash parts. 

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

<<< Just a little trimming was needed.  Some sheet metal shears performed very well.

NOTE: Apparently my setup has the new AC unit a little further from the firewall than Michael's installation.  I found I had some 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 footwell.

 


Here's the completed result. 



Charging with Refrigerant
Classic Auto Air has some specific instructions for charging a Street Rod Cooler III. 
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?

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 fail. That's the main reason systems sometimes get vacuumed for hours and hours. It's not the air so much as the water vapor that needs to be removed.


CHARGING WITH R134a FIRST
Classic Auto Air want you to use R134a.  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's my pressure readings after 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.
R134a Low: 27 PSI.  High: 270 PSI.



CHECKING FOR LEAKS
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 that was not installed 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
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.

R134a

Classic Auto Air specifies to use R134a in their systems.
I've never been much of a fan of R134a.
 
It was never as efficient as R12. But I did give it a good try in this conversion for a number of weeks.

134a VENT TEMPERATURE TESTS and PERFORMANCE
I spent a number of weeks testing with R134a.
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!



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





COMPARISON
DURACOOL versus R134a

I've preferred Duracool over R134a for a number of years. If you go to their site, READ THEIR FAQ SECTION.
http://www.duracool.com/

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.

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

LESS DURACOOL IS REQUIRED COMPARED TO R134a (or compared to R12a).
As mentioned, Classic Auto Air recommends R134a. 24 ounces of R134a was required for this conversion. 
The Duracool equivalent is 10 ounces. Yes, 10 ounces.
 
Here's a chart below showing exact 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.

WHAT MAKES DURACOOL DIFFERENT THAN R134A?
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 as high as possible 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.

The top two are ES-12 (Enviro-Safe) and Duracool.



Here an information video from Duracool. (3:41 length)
https://www.youtube.com/watch?v=E2ESleWa1nI





VENT TEMPERATURE PERFORMANCE WITH DURACOOL
Duracool is more efficient that R134a and in my system, it gets considerably colder.
Testing was done at idle and on the road.
 


INITIAL IDLE TESTING: 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.

2019 ROAD TESTING: While road testing the Volvo at around 55 mph with an ambient outside temp of over 100 F, I saw an extreme low vent temp of 25 F (PHOTO BELOW) however more common vent temps hovered around 31-32 F.

NET TEMPERATURE DROPS:
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.
 
  



PREVENTING FREEZE-UPS

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 AC system.

FREEZE UP 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 begin forming much heavier. If enough ice forms over time, it can eventually block the flow of air going through the evaporator. This 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 don't or can't climb under your dash to look for ice on your evaporator, another sign of ice forming can be found under your hood on your AC 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 to the compressor or to the accumulator. This is the return line for refrigerant returning from the evaporator in your dash to the compressor to be re-compressed. Ice forming on this line means things are really cold. Most often you won't see ice like this on a normally working AC system. A more common site might be some light frost or just cold beads of water condensation.



FREEZE UP 2.
Another type of freeze-up can occur if there are traces of moisture INSIDE your system.  If your evaporator dips below freezing (32 degrees 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 (in the line between the evaporator and compressor).  This reduced pressure can even become a vacuum if the blockage in your evaporator is severe. If this occurs, there's not much you can do but turn it off and wait for it to thaw out, which can be 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 (which contains a desiccant for moisture removal) will be a good idea if you suspect that an internal freeze-up has occurred, or if it hasn't been replaced in a long time (or ever), especially if the system has been opened or serviced a few times since being replaced. 

NOTE: The actual temperature of the refrigerant inside the evaporator can be as much as 8 to 12 degrees Fahrenheit COLDER than the evaporator exterior when the compressor is running.

RECEIVER/DRIER: 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. 

Also keep in mind that way back when I was using PROPANE in my original AC system (CLICK HERE), I was able to get very, very cold AC, but I eventually gave up on propane because performance was too inconsistent. Considering that experience now, I really think some of the problems might have been because of internal freeze-ups, since at one time I recall I got under the dash with my laser temp reader and measured the evaporator at 17 degrees Fahrenheit. Who knows? If I had found the below temperature controller back then (if it existed), it might have turned propane into a success.




TEMPERATURE CONTROLLER
2020-2021 Update
Here's a new device I've been testing to better control my evaporator temps.

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 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 to allow me to see the evaporator temperature and I have found that my evaporator has been getting considerably colder than 32 degrees Fahrenheit at times.The reason for this is likely because I'm using Duracool, which is more efficient that R134a and my temperatures can drop below freezing.
The programming functions for this unit allow me to cut power to the AC compressor if my evaporator becomes too cold.
My evaporator can definitely dip below freezing under some conditions because I'm using Duracool, so this device was bought to stabilize those temperatures.

I have the sensor tip taped to the outside of my evaporator outlet pipe. I then insulated it with some foam. The evaporator outlet pipe is the one that goes to the low pressure hose that returns refrigerant from the evaporator to the compressor.  
  
This device is small, about 3 inches wide.
Programming it was not difficult once you absorb what the instructions are telling you. For this programming you will use COOLING MODE, which I have circled on the second image below.
I set the programming to allow the AC compressor to run normally unless the evaporator dips to 34 degrees Fahrenheit. It then CUTS the compressor power and remains OFF until the temperature rises to 36 degrees.
This device should prevent the evaporator from getting too cold and it should eliminate any possibility of a freeze-up.
  
I've been using this for about 10 months as of August 2021. So far it seems to work really well.
During road tests with outside temps of 100 degrees Fahrenheit, my AC temps have been consistently at 36 degrees.

Here are images below of the instructions and programming guide.
CLICK IMAGE FOR LARGER PHOTO.
 

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


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

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