A/C Conversion

[David]

Audi released a TSB on converting to R134a. Check it out at http://www.ibiblio.org/tkan/audi/HC134A.pdfn

Now from a personal side...  First you have to decide whether you can live with an AC system that will never cool quite as well as it did with R12. Audi does not recommend converting any car with the York Type compressor with good reason (some other compressors can be converted easier, but I have not BTDT with any of those). I had mine converted and it's been a nightmare, but worked out in the end. On R12, from what I've heard, you should be getting vent temps at or below 40*F if the system is working properly. The best I can get out of my R134a system is the mid to lower 40s. Plus it takes a LONG time to get there, 10+ minutes for so on a hot day when interior temps start high. An example: the car and the vent thermometer (I just keep it in there) was showing 120 degrees. It took 10 minutes for so for the vent temps to drop to 50*F on #3 blower setting (takes even longer on high). It hit 45 degrees within another 5 minutes or so. But when it's 95 degrees out with high humidity, even 50 degree vent temps feel pretty good! So, do you think you could live with a slightly less efficient system?

Now, onto the worst part, the conversion. First, if you are going to do this, do it right. That means replacing: service fittings, dryer, all o-rings/seals, and the expansion valve. Then flush everything (have to remove the compressor to flush it). Now evacuate for a minimum of 4 hours and make sure it will hold a vacuum, now refill with ESTER oil and fresh R134a (ester is R12 & 134a compatible and it is a good conditioner of seals and o-rings) and keep you fingers crossed. One thing to keep in mind, R134a molecules are much smaller than R12 and will find even the tiniest ways to leak out. So if your hoses are even marginal, those will have to be replaced too. Doing a R12 to R134a conversion properly is pretty expensive. My conversion including a new high pressure flex hose and all the things above was over $700. Others may tell you to just go to your FLAPS and buy the $35 conversion kit. Sure, it might work, but from what I've experienced, it won't work well or it won't work very long. One other thing, make sure your radiator fan is healthy (works on all speeds if multi-speed and pulls well). It would also help to put a pusher fan in front of the AC condenser to added air-flow over it.

Overall, I guess I'm satisfied with the results. It works adequately and will make future recharges dirt cheap when compared to R12.

Well, sorry for the novel, but HTH, YMMV. Good luck.

Dave
1987 CGT Special Build 2.3
SE Virginia

>
> From: "Eric Pipas" <ericpipas at charter.net>
> Date: 2003/04/07 Mon AM 08:34:01 EDT
> To: "Quattro" <quattro at audifans.com>
> Subject: RE: A/C Conversion
>
> Has any one converted the A/C system from R-12 to R-134a on their pre R-134a
> cars. Any recomendations / pitfalls I should know about. My specific car is
> a 1987 5KCSTQ
>
>
> Thanks
>
>