POA/VIR valve adjustment for R134A

[jbs75]

Well... it seems there is an adjustment in POA valves to make the AC work better, if you do an R-134A conversion! Turns out(pardon the pun, but I couldn't resist), in the one of the ports of the POA valve there is an locknut/slotted screw adjustment, and turning that CCW 1/4 turn and locking again of course; reduces the pressure approx. 3-4 psi. which improves performance with R-134A! However it appears with VIR(on my 75, with not swell AC, even though I did everything right) valves there is no adjustment, is this correct? Is there only a spring, and what would you change it to? I suspect that the disparity between performance on some conversions I've heard here, is that some of the AC techs do this adjustment also.

Jim

[Vvette75]

Re: POA/VIR valve adjustment for R134A

Hi, I have a '75 also and saw the web site with info on adjustments. Looked in my factory manuals (for '74) and there are no adjustments to be made to the VIR/POA unit.

I have converted a few other cars to R-134A without any real problems using the so called quick kits. Compressors last and cooling is good. You will experience slightly warmer temps on a really hot and humid day in bumper to bumper traffic. Otherwise the system should act like an R-12 system.

You will always condense better while moving no matter what the refrigerant is. Being that the C-3 a/c is marginal at best, even when all things are correct, I would look into rebuilding what is their or changing to R-134a but also changing out the condenser for one that is about 20% larger in capacity.

John

[jbs75]

Re: POA/VIR valve adjustment for R134A

Everything has been redone. The POA valves actually do have an adjustment in them; it's just that the VIR does not. It appears that a spring is the only thing that controls pressure in it. The POA adjustment seems to makes a significant improvement.

[Don O'Connell #33101]

[jbs75]

Re: R-12 to R-134 conversion note

thanks; I heard that too, and I changed the hoses. In retrospect, I think it was a bad idea; because theoil, as it turns out soaks into the existing hose inner surface and is an effective block of R134A molecules. In addition the newer style lined hose does not hang on the barb of the existing connectors well. And you destroy an original hose. I'm trying to add to the knowledge base, keep someone from making the same mistakes I did, and hope I can find a VIR solution also. I know the outlet temp is not what it should be. Sometimes we grow too soon old, undt too late smart.

Jim

[Brandon K.]

Re: R-12 to R-134 conversion note

Where can I get more info on how to tweak my POA valve for the 134A??

Thanks, Brandon

[Bob Dransman]

Re: R-12 to R-134 conversion note

Jim,

I believe you are correct about the oil blocking the leakage of R-134A molecules through the R-12 hoses. I've had that discussion with a friend of mine who is in the biz.

Bob D.

[jbs75]

Re: R-12 to R-134 conversion note

Here is all the info in one place; and you can go to "aircondition.com" also

http://www.delanet.com/~pparish/retrofit.htm

Jim

[John Wire]

Re: R-12 to R-134 conversion note

Anyone tried R-414B? Not as expensive as R-12 and it will supposedly replace R-12 with no changes to the system.

John 75coupe