Andy's AC Post

[Al Powell]

Andy, I read your post below....here are the things which jump out at me:

1) Any compressor used with R-134A must have the proper seals for that 
refrigerant. R-12 has a larger molecular structure and the seals for it will 
NOT hold R-134A. It will leak out. If your compressor has the R-12 seals, it 
will not hold the refrigerant.  Make 100% sure that the compressor installed 
was set up for R-134A or the shop should remove it at their expense and 
install one which is correct for your application.

2) When replacing a compressor, you ALWAYS also remove and replace the 
drier/accumulator unit. If they didn't do this, they screwed up the job.  It 
must be done. This unit takes moisture out of the refrigerant, but due to the 
material in it, also retains the old lubricant used in the system.  See #3 to 
know why this is bad.

3) Before making this conversion, the entire AC system must be vacuumed out 
and preferably cleaned with solvent to remove any traces of the old 
lubricant. R-12 lubricant is incompatible with R-134A and all traces of the 
old lubricant must be removed before installing the new (correct) R-134A oil 
and re-charging the system.

4) If your old compressor failed, you can assume there debris and metal bits 
probably scattered through the hoses in the system. This makes it TWICE as 
necessary for the entire system to be cleaned out before installing new 
parts. There is also a small screen in the system called an orifice valve (or 
something similar) which probably has debris stuck in it, and should be 
replaced.

So the correct sequence for this job - and the only one you should accept - 
is:
- Vacuum out system
- Remove old compressor and dryer/accumulator
- Flush system to clear out debris
- Replace compressor, dryer and orifice valve. Compressor must have seals for 
R-134A installed.
- Re-charge system.

If they didn't do this - especially if they didn't replace the old 
dryer/accumulator, you will have continuing problems. if you accepted the job 
without them replacing critical parts, it's time to re-negotiate and get 
ready to write a big check.
************************************
Al Powell
Fort Collins, CO
powellae at home.com
cougfan1 at gocougs.wsu.edu
************************************

From: "Andy Goldberg" <andynyc at spacelab.net>
To: <quattro at audifans.com>
Subject: '89 100 - climate control failure
Date: Tue, 14 Aug 2001 23:22:43 -0400

I own a 1989 Audi 100 (auto, non-Quattro).  Last week I got a new a/c
compressor because the old one had failed.  The shop also upgraded my a/c
system to the newer refrigerant (non-Freon).

Anyway, for a few days, the a/c had worked better than ever.  Today, the
system failed.  There's no display at all inside the car and nothing coming
out of the vents.  This isn't just the fuse, since my glove compartment and
license plate lights still work.

When the old a/c compressor failed, the system also shut itself off.  My
repair guy said he got it going again when he installed the new compressor
by changing to a new fuse.  Now that there is no problem, however, I don't
know why the system shut itself off again.

Please help... it's hot down here!
-Andy Goldberg
andynyc at spacelab.net