AC problem

[malcolm@wedoit.ENET.dec.com]

Hi
I started this thread on the 20 valve list.
Maybe the rest of the quattro list might have some ideas.

Scott Malcolm

In a message dated 97-07-16 19:54:10 EDT, you write:

Hi
 
 I have been fighting with some AC problems for a few weeks and think I 
 might be close to being done.
 
 Along the way, I've replaced a water pump ( found during debug), some
 bad plug wires (fdd), a compressor, a receiver dryer, and an expansion
 valve.
 
 With the climate control on AUTO/LO/HI, I am measuring the center vent air
temp
 at about 25 degrees F below outside temp as displayed by the climate control
 outside sensors.
 
 
 Is this what other people are seeing? Car is a 1990 Coupe Quattro.
 
 Outside air temp of 88 is yielding a AC center vent temp of around 
 63 degrees. I am using a small Rat Shack electronic inside/outside
thermometer
 to check the vent temp.
 
 It seems like the AC was colder before this all started, but it has been
about
 4-5 weeks and I just can't remember anymore...
 
 Thanks
 
 Scott Malcolm
 1990 CQ
  >>
===================================================================

From:	WEDOIT::MALCOLM      17-JUL-1997 09:25:30.86
To:	MALCOLM,US2RMC::"Porsray@aol.com",20V
CC:	
Subj:	re: Help Ac Woes...

Ray,
Thanks for the response. I've mixed some answers below with the ">>"s.

Scott


From:	US2RMC::"Porsray@aol.com" 17-JUL-1997 00:58:26.08
To:	wedoit::malcolm, audi-20v@avs.com
CC:	
Subj:	Re: Help Ac Woes...

Scott, hate to say it but I think you have problems.  My 1990 Coupe
Quattro can freeze me out of the car under those conditions, without
too much trouble.   I can't remember what vent temps were (have a similar
digital thermometer), but will try to remember to test it over the next few 
days (it's about 90 with high humid. here in Pittsburgh)

Is this under all conditions, or only stop-&-go?

>> What I did was look at the starting and abslolute best it gets.
>> Right now with no real heat load ( dark or foggy/overcast), I can see 
>>24-25 degree differential.
>>
>> The entire sordid mess follows:
>>
>> This whole thing started out on the first 95+ degree day we had in june,
>> I hit the AC in the afternoon. I heard a sort of "poof", smelled a slight
>> burning smell in the ac air and the AC air started getting warmer. Drove home
>> in misery. 95+ degrees on the Highway in traffic. 
>>
>> Got home, and opened hood. Found AC belt inside out and off of pulley.
>> Go to Mechanic 1. Replace belts (all needed attention). Start car and 
>> hit AC. Sounds like someone is killing a pig under hood. Squeal sounds
>> metallic. Figure Compressor is f***ed. (Scott makes first error).
>>
>> Price compressors and do research. Go to mechanic 2. Mechanic 1 doesn't do
>> AC.
>> Mechanic 2 finds noisy water pump, wants to fix that noise first to be able
>> to ID ac noises later. Also notices that Compressor is not turning; Belt
>> very, very, very loose.
>>
>> So, we relace water pump. Replace belt with CORRECT SIZE. Compressor turns.
>> Scott drives home. Compressor makes sick noises. Gets worse with more RPM's.
>> AC will drop 15 degrees (ie if outside air temp on Climate control = 85, 
>> center vent will go to 70 degrees or so). After 25-30 minutes, AC temp 
>> will drift up to 1-2 below outside air. 
>>
>> So..., call Mechanic 2 and replace compressor and Receiver dryer. also 3
>> arcing plug wires. Get car back. AC now runs consistantly at 15-20 degrees
>> below outside temp. The 20 degrees is running at speed on highway, ac temp
>> set to LO, and fan on LO. Still not good enough; hardly  cools car at noon 
>> time. Have to open windows to be able to breathe..... 
>> 
>> So Back to mechanic2. He finds expansion valve full of crap.  Also replaces
>> flakey OXS sensor to help with engine stumble and rough running at idle and
>> during warmup. 
>> 
>> Everything he has done to date has contributed to the car running better
>> and the AC getting cooler. Oh yeah, he thinks timing belt was off one
>> notch when he replaced water pump. Mechanic 1 replaced TB last october.
>> Assured me water pump was fine. No problem. No need to replace. NOT.
>>
>> So, I pick up car last nite. AC will cool 20 - 25 degrees below outside.
>> can ride home comfortable (but not COLD). But it seems that it is still 
>> not back to 100%.  Starting to cost large $$$$$$$$. At 73 degrees this am 
>> on the ride in, the coldest I saw was 49.2 degrees. 
>> At 78 degrees it went to 52-54.  
>> 
>> So it is better. But how much more is it going to cost to get right.
>> 
>> Possible other problems may be: heater control valve allowing hot water
>> into heater core, warming up air; or some door not completely swapping 
>> to block outside air from mixing with AC air. The Recirc door does 
>> close after 1 minute, and fan speeds up then.
>>


Is the condenser fan going onto full speed when you switch on A/C?  

> Yes , fan goes on. The Climate control system seems to work correctly. I ran
> through a lot of the test. The only thing that seems to be wrong  is that it
> just doesn't seem cool enough. Every step of the repair process has 
> contributed to the AC getting a little better.

Did you fill it with Freon-12, or
the environmentally friendly but less effective F134?  
> good old Freon-12 "R-12"
If  you used F-12,
might
be a Freon leak. 
> I don't think its a leak. Its been charged 4 times now with all the part 
> swaps.
Bring it back to the turkeys who did the work.
> Probably will
> 
Ray Calvo (porsray@aol.com)
1990 Coupe Quattro  


> Later,
>Scott (looking for options)