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Discussion Starter · #1 ·
First let me start off by saying that no AC shop will touch my car. Probably because I might have the last R12 system on a MK3 in California, so I am stuck doing the swap myself. Anyone have any experience with the COMP 10PA17C PV4 or the COMP 10PA17C PV5 with R134: how cold do they get, how easy of an install, probably need a seal kit and the replacement fittings but anything else needed, how long does it take to change out roughly?

Been dealing with no AC all Summer and trying to get in time to install at the same time as a clutch and transmission rebuild planned for mid Oct.
 

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Can you clarify a few things?

Do you currently have an AC pump in your car?
Do you have all the pieces of the AC system in the car still?
Does the system have any charge in the system?

Overhauling the AC system involves taking out the evaporator core, replacing the expansion valve, replacing all the seals with the appropriate type (R134 uses a different type than R12), evacuating the system, replacing the drier, and filling it up with the appropriate amount of refrigerant. You'll need an AC gauge kit and a vacuum pump. Definitely doable for the DIY guy. Just make sure you understand the principles of the system.
 

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I retrofitted my own system and it took 2 or 3 days of work, not including the time to get 2 "new" pipes because I couldn't get the old ones apart to replace the o-ring in between. New and "new" parts came to almost $900.

If your compressor is still good, you can reuse it; same for the condenser. But, if you want to spend the money, you can upgrade the condenser to improve efficiency with R134a.

Also, get a quart of the proper solvent to clean out everything.
 

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^Maybe? If you're taking apart the system to freshen up the seals, either way is about the same work.

Just need to asses where you're system is currently at. A manifold gauge would at least be able to tell you if the system has something in it.
 

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However you can get it done I think converting to R134a is the best plan. The gas is affordable and easy to get and @Whoosh10 mentioned earlier if you have to replace seals you might as well convert. I have been satisfied with my AC running R134a. I topped off the charge with this last spring and AC has worked great all summer:

Bottle Liquid Product Azure Fluid
 

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Why don't you want to buy eBay R12 and just charge it up?

An auto shop that deals in classic cars should still have workable R12 equipment. Ask at your favorite 'regular' shop to see where to take the car.
 

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I've said it before: be real careful buying R12 off eBay as basically everything there listed as R12 is not actual real R12.

R134a is also on the way out, but you can still get cans for $6. Stock up now!
 

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However you can get it done I think converting to R134a is the best plan. The gas is affordable and easy to get and @Whoosh10 mentioned earlier if you have to replace seals you might as well convert. I have been satisfied with my AC running R134a. I topped off the charge with this last spring and AC has worked great all summer:

View attachment 280426
Also make sure it doesn't have the sealer stuff in it. The Walmart store kind is pure r134a. Anything with stop-leak is just asking for trouble later down the road imo.

Another consideration (and I think why mine leaked out) is the compressor shaft seal. Not sure if you can replace that easily, but that is also an r12 seal to my knowledge. R134a will leak out through that. Additionally the top plate o-ring on the compressor should be changed. I don't think I changed that one either. My ac blew very nice and cold for a year and died this summer. Now I get to go back and redo all my work. The ac system cleaner is also an important overlooked step. Definitely use the solvent to purge it of any old oil and general crud. Don't try and skip steps like I evidently did 🙂 Cry once, buy once, etc.
 
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Also make sure it doesn't have the sealer stuff in it. The Walmart store kind is pure r134a. Anything with stop-leak is just asking for trouble later down the road imo.
The R134a can I showed contains an additive that makes the seals swell up, as far as I know thats it. My system was converted before I got the car and I don't have any info on what was done. By the looks of things it was a very minimal job and I will have to go back at some point and replace components that should have been changed out for the conversion. For now it works and I have other things to attend to.
 

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The R134a can I showed contains an additive that makes the seals swell up, as far as I know thats it. My system was converted before I got the car and I don't have any info on what was done. By the looks of things it was a very minimal job and I will have to go back at some point and replace components that should have been changed out for the conversion. For now it works and I have other things to attend to.
Hey, if it works! I was just referring to a newly retrofitted system with everything replaced and renewed. Truthfully on an old/unknown system I doubt that additive would hurt and it may in fact help.
 

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Discussion Starter · #15 ·
I have a gauge set and vacuum pump, will need an expansion valve. Found some interdynamics r12 cans on ebay. Just need to pull vacuum to check for leaks. @Whoosh10 I looked a little bit for r12 seals and could only find the green kind that say they are for r12 r134 and r1234, you are saying they are not the same/not compatible with all refrigerants. Is my only option to use my old seals or is there something that I can buy to keep using r12?
 

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I'll let the more knowledgeable give you the definitive answer.. but I think the old R12 seals just wouldn't hold up to R134a. You might be fine with those greens ones for R12 though. I just can't give you a definitive answer.

@SupraMikeCT, this question seems right up your alley.
 

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I'll let the more knowledgeable give you the definitive answer.. but I think the old R12 seals just wouldn't hold up to R134a. You might be fine with those greens ones for R12 though. I just can't give you a definitive answer.

@SupraMikeCT, this question seems right up your alley.
@Woosh10 is correct, the old black seals and O rings will not hold up to R134a refrigerant. The green and the Toyota red O rings will work with either R12 & R134a.


Green manifold gasket for the MK3's Supra ND 10PA17 compressor manifold when converting to R134a:


EDIT:
BTW, I would use Ester oil instead of PAG if I were converting to R134a. Ester oil is more compatable with any remaining mineral oil than PAG oil.
The desiccant used in new receiver/driers also work for both refrigerants
 

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Discussion Starter · #20 ·
@Woosh10 is correct, the old black seals and O rings will not hold up to R134a refrigerant. The green and the Toyota red O rings will work with either R12 & R134a.


Green manifold gasket for the MK3's Supra ND 10PA17 compressor manifold when converting to R134a:


EDIT:
BTW, I would use Ester oil instead of PAG if I were converting to R134a. Ester oil is more compatable with any remaining mineral oil than PAG oil.
The desiccant used in new receiver/driers also work for both refrigerants
I want to maintain r12, so I will swap over the seals to green if I have leaks from a vacuum test.
 
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