The great 240 AC system information dump + How to improve AC performance

[HiSPL]

The suggested Diesel compressor in the OP. It's mentioned that it is designed for efficiency at lower rpm. Is there any problem with reving it out to 6k or more? Or for that matter running it at 3k cruise for an hour or more? Am I better off sticking with some other compressor? Or is it not a big deal to send it with the Sanden Diesel compressor?

[Epic2112]

Originally Posted by Marvelous3

I’m not sure if anyone answered your question but yes, the condenser will bolt into the core support. The lines are different though. You’ll need new lines a ways to deal with 134a anyways so...

Well, what I'm really wondering is if the fittings on the 91 hard lines will bolt up to the 93 condenser.

My car was converted to 134 a good few years ago so all the rubber hoses are 134 compatible, but it's since all leaked out. Since I'm going to have it open to atmosphere when I replace the accumulator and orifice tube anyway I'm thinking I'll drop in a 93 condenser.

Here's what I'm thinking after poking around on the web a bit. The immediate connection to the condenser on each side is a hard pipe. Each of those connect to a rubber hose (one to the compressor, one to the evaporator). The part numbers listed in VIDA for those rubber hoses specific to MY 93 are listed at some online retailers as fitting 91 - 93 cars. I'm guessing the different numbers in VIDA for 91 & 92 are due to the rubber being for r12 systems instead of 134. Since no one is using r12 anymore, I think all the hoses being sold now are r134 compliant. And if they're listed as fitting 91 - 31 the threads on the fittings must bolt right up. That leaves the two hard lines between the condenser and those hoses. There are different part numbers for all of them in VIDA, each year has their own lines. I have no idea if this is because fitting size/threads/whatever changed, or maybe some minor thing like the location of the pressure switches was moved or something.

Unless someone happens to have all of this stuff laying around and compare them side by side, I think I'm going to have to hunt down those pipes and cross my fingers. If I figure anything out I'll update here. There's a 93 in the yard nearby, I guess I'm going parts-pulling...

[wcirco]

Originally Posted by dbarton

I'm disappointed. I would have hoped to see more information about HC refrigerants. I won't uselessly argue that my Duracool 240 blows plenty cold, because I know different cars have different results all the time. I have a different argument.

CLAIM: "All of these HC refrigerants have very little mass at the pressures used, meaning they will not remove heat as efficiently as R12 or even 134A."

I'm not a physicist, but it seems to me that drawing a conclusion on an HC refrigerant cooling potential this way makes it seem inferior based on less MASS. Can anyone expand on the cooling potential of HC refrigerants in comparison to R134a based on MASS?

I did some reading. My research suggests something different. Something call LATENT HEAT. This involves the evaporation of the refrigerant in the refrigeration cycle, which is what produces cooling in your evaporator. From what I read, the latent heat of a refrigerant should be as large as possible for best cooling potential in an evaporative system. Also, 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. Less mass doesn't sound like a bad thing to me.

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, HFC-134a and Duracool, among others. It can be found at the following link. https://info.ornl.gov/sites/publicat...s/Pub57507.pdf

It describes LATENT HEAT as the amount of heat unit per mass required to convert the refrigerant from liquid to vapor.
This means that a refrigerant with a larger latent heat value can remove more heat.

Dave B

Alright so my hypothesis was wrong. For the record I don't claim to be an expert, only knowledgeable enough to get myself into trouble
12A is technically a better refrigerant. Although any refrigerant used in a system that isn't optimized for it will not work efficiently. The poor performance I was seeing could be a result of the large variance in low side pressures in the orifice tube system. After charging the system with 12A I noticed the compressor would cycle very quickly. Trying multiple different orifice tubes yielded no better results. I have not personally tried it in a TXV system to compare performance however. To me it would seem radical modification (huge compressor possibly) of the orifice tube system would be needed to make 12A work as effectively as 134A. With the 242 getting close to roadworthy I may do some experiments with the TXV system before swapping it out. Still have a half case of Frostycool to burn...

[HiSPL]

Originally Posted by HiSPL

The suggested Diesel compressor in the OP. It's mentioned that it is designed for efficiency at lower rpm. Is there any problem with reving it out to 6k or more? Or for that matter running it at 3k cruise for an hour or more? Am I better off sticking with some other compressor? Or is it not a big deal to send it with the Sanden Diesel compressor?

Anyone?

Can you over-rev a compressor?

[wcirco]

Originally Posted by HiSPL

The suggested Diesel compressor in the OP. It's mentioned that it is designed for efficiency at lower rpm. Is there any problem with reving it out to 6k or more? Or for that matter running it at 3k cruise for an hour or more? Am I better off sticking with some other compressor? Or is it not a big deal to send it with the Sanden Diesel compressor?

Mine is still blowing ice cubes for year and 8K miles since install. I regularly cruise 3Krpm + with the ac on.

Sanden rates the compressor for 6Krpm max.

[wcirco]

Originally Posted by Epic2112

Well, what I'm really wondering is if the fittings on the 91 hard lines will bolt up to the 93 condenser.

My car was converted to 134 a good few years ago so all the rubber hoses are 134 compatible, but it's since all leaked out. Since I'm going to have it open to atmosphere when I replace the accumulator and orifice tube anyway I'm thinking I'll drop in a 93 condenser.

Yes it is a simple remove and replace install, no modification needed for 91-92 cars for the 93 condenser.

[HiSPL]

Originally Posted by wcirco

Mine is still blowing ice cubes for year and 8K miles since install. I regularly cruise 3Krpm + with the ac on.

Sanden rates the compressor for 6Krpm max.

Cool.

[TestPoint]

Too much thinking. Not enough doing.

In my V8 conversion I used the Ford 2000 model year compressor, new aluminum horizonal condenser, new R134a expansion valve, new hoses, rings and dryer. Flushed everything, vacuumed down and filled with Walmart $5 R134a to 30 psi on low side. How's that for a technical spec?

Seven years and 20k miles later still get 46 degrees vent temperature at 83 ambient. Just checked recently. Still setting at 30 psi. That's not in the 30's but 10 degrees below Volvo specs for my '82.

[Wood]

Originally Posted by dalek

I my notes I have the default 960 compressor is the Sanden SD7H15. True or false?

I pulled one from a '95 940, but it was a Sanden clone. Just one anecdote for that.

[dbarton]

Originally Posted by wcirco

12A is technically a better refrigerant. Although any refrigerant used in a system that isn't optimized for it will not work efficiently. The poor performance I was seeing could be a result of the large variance in low side pressures in the orifice tube system. After charging the system with 12A I noticed the compressor would cycle very quickly. Trying multiple different orifice tubes yielded no better results. I have not personally tried it in a TXV system to compare performance however. To me it would seem radical modification (huge compressor possibly) of the orifice tube system would be needed to make 12A work as effectively as 134A.

Optimized is a good word. Smarter people than us designed these systems around the available refrigerants at the time. My experience is strictly with TXV cars, so I don't know how Duracool would or should be expected to work in an orifice tube Volvo.

I originally installed R134a in my Classic Auto Air conversion (which use a TXV) and got disappointing results. Otherwise I wouldn't have changed to Duracool, which made all the difference and brought temps down 10-15 degrees.
Dave

[Cwazywazy]

Sanden gang. This one was $160 shipped on ebay.




Here you can see how much I had to notch my bracket to make the discharge line fit. You can also see the bolt in r134 charge port adapter I put on the suction line. I then had to make a spacer for the rear upper bracket as vishmutzy detailed. Still need to put the rest of my car back together before I can charge it up and try it out.

I bet this Sanden would be a direct bolt in for anyone with a D24 since the compressor that came on those engines has the same style ports.

By the way, does anyone actually understand the TXV adjustment? Everywhere I read about 240 AC it's 2 or 3 turns for r12 and 7 turns out for r134, but I had a spare late 80s HVAC box with what certainly appeared to be the original undisturbed TXV and when I removed it, it was set to 13 turns . IIRC the one in my old wagon was set to 12 turns, dunno if that one was original or not.

[Epic2112]

Originally Posted by wcirco

Yes it is a simple remove and replace install, no modification needed for 91-92 cars for the 93 condenser.

Almost, but not quite. I pulled a bunch of parts off a 93 in the junkyard. The condenser bolts in with no modifications (but beware those decades -old rubber mounts, they all crumble when you try to loosen them), however the hardline that attaches at to the top connection point on the condenser will need to be swapped out for the line from the 93.

The top connection on my original 91 condenser is right near the top of the condenser. The top connection on the 93 condenser is about halfway down. The hardline will thread on to the condenser, but it doesn't really fit since it's longer. It took me a while to figure out what the problem was. I'm going to have a local place make a new hardline for me, since the one from the junkyard car was in rough shape, and then I expect it'll bolt right in (with a lot less wrestling).

[culberro]

Originally Posted by dbarton

Optimized is a good word. Smarter people than us designed these systems around the available refrigerants at the time. My experience is strictly with TXV cars, so I don't know how Duracool would or should be expected to work in an orifice tube Volvo.

I originally installed R134a in my Classic Auto Air conversion (which use a TXV) and got disappointing results. Otherwise I wouldn't have changed to Duracool, which made all the difference and brought temps down 10-15 degrees.
Dave

I'm using 2 cans of Envirosafe refrigerant in my '92 244 DD. It blows 36-38F out of the vents when moving down the freeway when temps are 90F ambient. At a stand still, the vent temps are running around 40-42F. Absolutely necessary in a all black car with no tint

All I did before the install:

• Cleaned and flushed the entire system. The original orifuce tube was PACKED with crud. I just cleaned out the compressor and filled it with oil through the oil fitting on top of the compressor housing.
• Replaced all o-rings in the engine bay side of the system (I'll get to the cabin side when/If I replace the blower motor)
• Installed an self-compensating orifice tube from rock auto (~$10)
• Vacuumed the system, and then charged it with the appropriate amount. Which just happened to be 2 full cans of Envirosafe.

That was just over a year ago, and the system is still blowing just as cold.

[QisofrKuin]

This thread could not have come at a better time.
I recently bought an '81 244 DL, and I was told that the ac system had been converted to R134a at some point, and it looks to my untrained eye that they replaced the drier and the compressor, though admittedly I'm not certain. However, the line that leads from the drier through the firewall to the evaporator is damaged, so all the refrigerant is long gone and I can't test anything yet. Perhaps some of you who have updated your systems and had to redo the tubing can tell me, did you have to take apart the dash to replace the drier-->evaporator tube? Or can that be replaced without such drastic action?

[wcirco]

Originally Posted by Epic2112

Almost, but not quite. I pulled a bunch of parts off a 93 in the junkyard. The condenser bolts in with no modifications (but beware those decades -old rubber mounts, they all crumble when you try to loosen them), however the hardline that attaches at to the top connection point on the condenser will need to be swapped out for the line from the 93.

The top connection on my original 91 condenser is right near the top of the condenser. The top connection on the 93 condenser is about halfway down. The hardline will thread on to the condenser, but it doesn't really fit since it's longer. It took me a while to figure out what the problem was. I'm going to have a local place make a new hardline for me, since the one from the junkyard car was in rough shape, and then I expect it'll bolt right in (with a lot less wrestling).

Interesting, didn't run into that issue with my '91. The fittings were in the same spot as the old condenser. I did use a Nissens replacement condenser instead of one pulled from a '93 though.

[white855T]

Originally Posted by wcirco

Interesting, didn't run into that issue with my '91. The fittings were in the same spot as the old condenser. I did use a Nissens replacement condenser instead of one pulled from a '93 though.

Is 940422 the part number for the nissens a/c condenser?

[wcirco]

Originally Posted by culberro

I'm using 2 cans of Envirosafe refrigerant in my '92 244 DD. It blows 36-38F out of the vents when moving down the freeway when temps are 90F ambient. At a stand still, the vent temps are running around ambient.

This was similar to what I experienced. Most of my commute is spent in stop and go traffic so the lack of cooling at low speeds was less than ideal. 4 years ago I was ripping the AC system out of my 740, now I cant handle no cold air for 20 minutes

[Epic2112]

Originally Posted by wcirco

Interesting, didn't run into that issue with my '91. The fittings were in the same spot as the old condenser. I did use a Nissens replacement condenser instead of one pulled from a '93 though.

Two possibilities:
1) My 91 is an SE, which is a bit of an oddball car in a few ways that generally don't matter (different trim pieces and interior "options" as standard). Unlikely, IMO, but maybe there were some slight differences with the A/C system between the SEs and other 91 models. It would be the first time I've seen something on this car deviate from the other 91 cars in any way that wasn't cosmetic, though.

2) The Nissens condenser you bought could be a one-size-fits all. There's only maybe 2 or 3 inches of difference between the location of the fitting on my 91 condenser and the one from the 93, and I was able to wrestle the original line into place. I bet if the Nissens piece splits the difference it'll fit OK with either hard line. That way they only need to make one part that will be a replacement for 93 cars, and an upgrade for 91 & 92s.

[jjona5]

I just moved the bracket to the other side and used some spacers to get it out of the way of the lines.

Originally Posted by Cwazywazy

Sanden gang. This one was $160 shipped on ebay.




Here you can see how much I had to notch my bracket to make the discharge line fit. You can also see the bolt in r134 charge port adapter I put on the suction line. I then had to make a spacer for the rear upper bracket as vishmutzy detailed. Still need to put the rest of my car back together before I can charge it up and try it out.

I bet this Sanden would be a direct bolt in for anyone with a D24 since the compressor that came on those engines has the same style ports.

By the way, does anyone actually understand the TXV adjustment? Everywhere I read about 240 AC it's 2 or 3 turns for r12 and 7 turns out for r134, but I had a spare late 80s HVAC box with what certainly appeared to be the original undisturbed TXV and when I removed it, it was set to 13 turns . IIRC the one in my old wagon was set to 12 turns, dunno if that one was original or not.

[culberro]

Originally Posted by wcirco

This was similar to what I experienced. Most of my commute is spent in stop and go traffic so the lack of cooling at low speeds was less than ideal. 4 years ago I was ripping the AC system out of my 740, now I cant handle no cold air for 20 minutes

Made a typo in my original post. At low speeds the vent temps are actually around 40F.

[toms_elleck]

Originally Posted by TestPoint

Too much thinking. Not enough doing.

In my V8 conversion I used the Ford 2000 model year compressor, new aluminum horizonal condenser, new R134a expansion valve, new hoses, rings and dryer. Flushed everything, vacuumed down and filled with Walmart $5 R134a to 30 psi on low side. How's that for a technical spec?

Seven years and 20k miles later still get 46 degrees vent temperature at 83 ambient. Just checked recently. Still setting at 30 psi. That's not in the 30's but 10 degrees below Volvo specs for my '82.

Can you tell me more about the condenser that you used?
Was it a Volvo unit or did you find something else that worked? I read on here about a 1991 Ford Explorer unit possibly fitting in place, but does not use threaded fittings.

[TestPoint]

I found an ebay unit that fit by dimensions H & V. Probably would have been better off buying about 1 inch smaller horizonal as I had to drill 4 holes to make it fit. About $50. The connections are standard AC fittings. Only the external connections are specific to old/new connectors.

[toms_elleck]

Does anyone know if the 1991-1993 evaporator come close to fitting in place of the early evaporator? Maybe with a little trimming and such?
I'm just weighing my options, trying to determine whether I really need to swap my airbox to the late style.

[bobxyz]

Try this A/C thread: http://forums.turbobricks.com/showth...=330298&page=3

[toms_elleck]

Originally Posted by toms_elleck

Does anyone know if the 1991-1993 evaporator come close to fitting in place of the early evaporator? Maybe with a little trimming and such?
I'm just weighing my options, trying to determine whether I really need to swap my airbox to the late style.

For anyone searching in the future who may be interested in this information, I found dimensions on the Four Seasons website.

OLD evaporator:
P/N: 54603
dimensions: 3 x 8 x 9.5 inches
Link: https://www.4s.com/en/ecatalog?part=...ype=p&search=s

NEW evaporator:
P/N: 54502
dimensions: 2.8 x 7.25 x 13.5
Link: https://www.4s.com/en/ecatalog?part=...ype=p&search=s


The new style evaporator would actually come close to fitting in the old airbox, but the left and right sides of the box would need to be modified as it's 4 inches wider. The lines also interface with the firewall- I am not sure how that would pan out, but I assume you could position the airbox so the lines fit into the firewall, and then complete the modifications to seal up the sides of the airbox. You'd also have to figure out your own expansion valve, as that will no longer be integrated onto the evaporator.

I chose to simply use the early one and hope that it will perform well enough with the GM compressor (LS swap) and large aftermarket condenser. If it does not, then I may get crafty with the airbox so that the new style evaporator will fit.