AC recharge R12 to R134?

Joshua Van Tol
Thu, 6 Jun 2002 17:20:42 -0500

>Well, I just went through a NIGHTMARE conversion on my Coupe GT.
>Audi officially doesn't recommend conversion of cars with the York
>or Delco-Air type compressors. I'm not sure what kind you car has, I
>think it has a

Those old compressors are junk, and don't work particularly well,
even with R-12. Even the Densos aren't that great.

>Nippondenso which is OK to convert but you should check out the TSB
>on conversion. It can be found at
> Make sure your car has
>one of the compressors that can take R134a. Also, you NEED to
>replace the expansion valve and receiver/dryer as well as ALL
>o-rings (must use the "green o-rings). Make sure he properly flushes
>ALL parts/lines (many parts must be removed to properly flush such
>as the compressor). If the old oil for R12 remains and you put the
>proper oil for R134a in, it will turn to sludge quickly causing your
>compressor to freeze up. This is NOT a cheap

Everyone used to belive that "sludge" theory. Turns out it just
doesn't happen. That said, it's a good idea to get as much of the
mineral oil out as possible, and you must run a compatible oil. Also,
it is a very good idea to replace all the o-rings, the receiver
drier, or accumulator (whichever your car has) and the expansion
valve or orifice tube, whichever your car has. Replacing expansion
valves can be optional if the system is in good condition, and the
valve isn't gunked up. Orifice tubes, however, are so cheap it's
foolish not to replace them.

BTW, sludge formation is a symptom of water in the system, and the
accompanying depleted/degraded drier or accumulator dessicant

>  thing to do properly, but it can be done. I've discovered that it
>CAN be done even on cars with York compressors, but since there was
>no documentation on what all had to be done, it was a trial and
>(lots of) error process. BDTD.

As a BTDT point, my 87 5kcstq has been running R134a for about 2
years now, works great. My friend has an 89 200tq and it was just
converted, and works great too.
Joshua Van Tol --