[s-cars] UrS HVAC Question

[djdawson2 at aol.com]

Disconnect the wire that goes to the back of the compressor clutch.  Apply 12 volts to that, and the clutch should engage.  You could test at that point to see if any cooling is going on at all... or if there are "bad" noises.
 
Yes, the port is up front.  You can hook up a high side guage to that... engage the clutch, and see what's there.
 
 
-----Original Message-----
From: sryoung at trane.com
To: s-car-list at audifans.com
Sent: Fri, 11 May 2007 1:59 PM
Subject: [s-cars] UrS HVAC Question



Group collective...

Patient is a 94 S4 with 140K.  When I bought the car a few years ago, I
had a problem with the HVAC from the start.  The system would always
throw heat, unless the temp was set to "LO", at which point I would get
sufficient cooling.  Being new to the UrS clan, I bought a used
replacement CC head unit.  This was not the problem, as we would all
expect.  After more research, it seemed more like a temp flap servo.  At
this point, I had mods to do, so this went unaddressed.

Fast forward, those mods are complete and I am using the car again.  Now
I get heat all the time, even in "LO".

Fast forward more and I have all the consoles out for a SS install.  I
figure this is the time to figure this out once and for all.  I have
tested all three flap servos by cycling temp, defrost, and dash > feet.
All servos visually appear to stroke fully and operate as intended.  I
have 00.0 on channel 01.c, so no codes.  My guess is that I am out of
refrigerant.

I know these A/C systems are a PITA to work on and charge due to a lack
of a low pressure port, but is there a way to test the compressor
operation?  I assume it wouldn't engage due to a low pressure compressor
cutout.  Where is the high pressure tap so I could check for a system
charge?  Is it right at the condenser in front of the radiator?

Am I missing something in my logic?  Any help is appreciated, and TIA. 

Regards,

                TRANE
Steven Young
Local Operations Manager
Albany Office
*  Tel. (518) 724-1453
* Fax (518) 785-4359
* sryoung at trane.com

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