A/C Retro Fit?

Schaible, David David.Schaible at penw.com
Wed Jun 19 09:19:19 EDT 2002

I was told the same thing about the oil by several different people, my compressor failed on me last year so I replaced it with the R134A conversion.

-----Original Message-----
From: Gene Caldwell [mailto:gene.ghc at verizon.net]
Sent: Wednesday, June 19, 2002 5:24 AM
To: Jobe Tichy; 200q20v at audifans.com
Subject: Re: A/C Retro Fit?

Jobe Tichy wrote:

>[ Converted text/html to text/plain ]
>Has anyone installed the A/C retrofit to R134A kit from Blau (or other
>source)?  It's super cheap and apparently comes with instructions for Audi
>installs.  I think it is that time to do something--either buck up for R12 or
>Anyway, my concern is that Blau states that the dryer "may" need to be
>replaced.  My question is whether anyone can confirm whether it does/does not
>need to be replaced.  Does it depend on the condition of my particular dryer?
>Is it something necessary regardless, for a clean upgrade?  Any help would be
>great--I know nothing about A/C other than it's gonna be needed SOON!
>'91 200tq 20v

I believe the main issue when switching the A/C working fluid from R12
to R134A is lubricating oil.  R12 systems use a mineral oil, which is
carried around with the working fluid  and thus gets all over the inside
of everything (as it is supposed to).  Depending on who you listen to,
R134A either isn't "heavy" enough or has the wrong chemical makeup,
needed to successfully carry this mineral oil in suspension to all the
pieces that need it (like the compressor).   So systems which use R134A
employ a different (synthetic) oil referred to as "TAG".  I don't know
what that stands for, if anything.

The canister referred to as "accumulator", "dryer", "receiver" has a
fair amount of oil accumulation.  When switching from R12 to R134 the
main thing is to remove as much of the mineral oil as possible and
replace with TAG oil.  Replacing the accumulator ($50 from TPC) is
usually considered prudent.  I've heard varying opinions regarding the
compressor.  Some want to just replace it to lessen chances of trouble
down the road, and possibly take in more money(?).  Others I have talked
with will remove the compressor (if it is basically good) and let it
drain for a few hours.  Flushing the mineral oil out the remaining
system plumbing seems to be an optional step, depending on the
enthusiasm of the A/C technician.


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