|VOLVO 240 AC PAGE
And Classic Auto Air AC Installation Project
|UPDATED: April 16, 2023 CONTACT|
O M A I N S
|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
|240 Original AC INTRO
||Stock 1991 and LATER 240 AC
||240 AC Systems Overview
|Later 240 AC Wiring Diagram
||PROPANE in your AC?
||DURACOOL R12 Replacement
|First Classic Auto Air
Installation in a 240 (2016)
|My Classic Auto Air
Installation Starts HERE (2017)
|Classic Auto Air
vs Vintage Air
|New AC Ducts Installed
||AC Hose Assembly
Traditional Crimp and Other Alternatives
|RESULTS: 134A vs Duracool
||AC Too COLD?
Preventing Evaporator FREEZE-UPS
|Evap Temp Controller
for Precise Temps
|Volvo 240 AC.
INTRODUCTION and BASICS.
enjoy taking long road trips. Taking a long road trip in a hot car in
hot climate does not sound like 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.
The AC was later improved for 1991-93 cars when a differently design system was used.
Image below shows a pre-1991 240 AC, showing an AC drier on the right fender.
|So then later 240 AC is better?
The answer is YES!
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 refrigerant.
Image below of 1991-93 240 AC (showing larger accumulator/drier near firewall).
Late 240 AC Components
Here's an overall image of the entire 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 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 Improvement 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.
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.
FRONT CONDENSER INFO
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 1991 240
Here's a photo of a 240 ORIFICE TUBE being removed.
An orifice tube 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 tube is generally made of a metal tube with a chamfered inlet, with a plastic valve body. An orifice tube can become clogged if debris or contaminates get into the system due to it being left open or in the case of a compressor failure. In this case the tube should be replaced.
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.
USEFUL 240 AC PART NUMBERS
1395590, 3513066 Compressor 240 to up 1992 R12.
6841028 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).
9131972 Accumulator 240 1993 R134a (LHD).
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.
|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.
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 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.
|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 so many people needed to know where all those vacuum hoses in your dash go.
For more vacuum diagrams, go to my Vacuum Diagram Page
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
Here's an alternate diagram below of the condenser later 240 fan circuit.
Normally the condenser fan only comes on then the Pressure Sensor is closed.
This mod below changes TWO wires on the fan relay (see the blue boxes below) to allow the fan to run anytime the AC Compressor circuit is activated.
|CFC 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 worldwide in 2010.
R12 is dichlorodifluoromethane, a colorless gas sold under the brand name Freon-12 or R12. It's classified as a chlorofluorocarbon (CFC).
Thermal Expansion Valves were used in 240 R12 systems 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, the TXV cars using or upgrading to R134a would have used replacement valves that were set or adjusted for R134a. This raises the question about DIY users doing their own adjustments on TVXs to suit R12, R134a or another suitable refrigerant.
The 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: https://www.forums.turbobricks.com/showthread.php?t=213526
In 2012 gave up on propane and began trying Duracool 12a 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 eventually got pretty good cooling on the highway, but I still found problems at idle (although it seemed to get 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 satisfied with my AC.
CLICK HERE TO SEE MUCH MORE ABOUT DURACOOL AND MY ULTIMATE RESULTS.
Reputations of Aftermarket AC Systems
Over the years I would come across custom hot rods at car shows with custom retrofitted 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 develop in retrofit 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 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.
|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
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 system, here's a pretty good video that will help with the basics.
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.
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 for the 240 DYNAMAT Installation Page
If you have any suggestions to improve the information in this page, please email. Thanks, Dave
|Introduction of the Street Rod Cooler III
There were not many photos of this unit in their site, so I have included some here.
The above photo is from Aris (from Greece) taken during his 240 build, which can be found here: http://forums.turbobricks.com/showthread.php?t=310632
The above photo shows the original black 1985 condenser, which is made from TUBE and FIN construction. All 240s up through 1990 received a black condenser similar to this. The original size was about 15.5 x 26 inches.
Aris then fitted a 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 to the compressor. The bottom fitting is smaller (#6 male) and is connected to the hose to the drier canister. I have more info about AC hose sizes further down in my 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 or a variety of other places if you search: Universal AC Condenser. A universal condenser will be available in different sizes, but one in the approximate size of 16 x 24 inches like the above one will fit OK in any 240 (or see below for the 16 x 26 inches 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 is unpainted, but typically the factory condensers were BLACK.
If you have the older style (below), you can install a later one like this above with a bit of work or you can buy a universal type.
The design difference is pretty easy to see compared to this early style condenser above from a 1990 240.
I know you'll want to know this: A straight swap may not be possible. The locations or positions of factory AC hoses may not be quite the same between the two styles in a 240. 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 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 low-profile 16 inch low-profile Spal PUSHER fan on the front of the universal condenser. Spal fans are an excellent choice. Very well made and very powerful. A 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 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 mounted some more serious horns under the car. I have a HORN PROJECT PAGE for that.
|Mounting the new AC Box in the DASH.
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 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.
240 HEATER HOSE ORIENTATIONAt 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.
2021 Update: Larger Ducts Added (click here)
<<< 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
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.
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.
Hose Parts Inventory List
This list covers all AC hoses. All fittings are aluminum. Below items were ordered from coldhose.com.
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.
Classic Auto Air has some specific instructions for charging their AC systems.
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 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.
I tried to play by the rules.
CHARGING WITH R134a FIRST
Classic Auto Air wants you to use R134a.
<<< 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.
CHECKING FOR LEAKSThis 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.
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.
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.
I've preferred Duracool over R134a for a number of years. If you go to their site, 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.
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 table below showing exact conversions
(from the Duracool website FAQ section).
Here an information video from Duracool. (3:41 length)
ULTIMATE 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 27º Fahrenheit with an ambient temperature of 80º 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 27º and 32 º 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 100º F. After initial start-up in my garage, vent temperature at idle was 46º F. Since 46º 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 100º F plus outside temperature. It recorded a vent temperature of 43º F. My 240 wasn't too far behind that.
2019 SUMMER ROAD TESTING:
While road testing at 55 mph with an ambient outside temp of over 100º F, I have recorded low vent temps of 25º F (PHOTO BELOW) however more common vent temps seemed to be around 31-32º 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.
NET TEMPERATURE DROPS:
So it appears my potential vent temperature drop below ambient is around 53º-55º F at idle and around 68º-74º F degrees at 55 mph. This is awesome cooling compared to before!
Yes, this kind of performance makes me smile.
Any temps below freezing can have a potential negative affect. You should read the BELOW section on preventing freeze-ups.
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 (32º 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 17º 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.
|EVAPORATOR TEMPERATURE CONTROLLER
Injecting some higher tech into AC control.
Here's a new device I've been using for a while to control my evaporator temps 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 32º 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 32º Fahrenheit. It then CUTS the compressor power and remains OFF until the temperature rises one degree to 34º.
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.
WIRING DIAGRAM FOR MY INSTALLATION
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 use to turn on the compressor.
QUESTION: 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, like me.
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.
NOTE: 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. CONTACT
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.
CLICK IMAGE FOR LARGER PHOTO.
A downloadable or printable PDF of these instructions is here: https://www.davebarton.com/pdf/BayiteTCF3A035TempController.pdf
Update: May 2022
I've been using this system along with the above added TEMP CONTROLLER above for two 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 (because I'm using Duracool), my evaporator would definitely dip well below freezing. So this device has been very successful at stabilizing temperatures to prevent a freeze-up.
If you've done an AC upgrade to your Volvo that you can share 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 suggestions to improve the information in this page, please let me know. Thanks, Dave
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