'88 5K Air Conditioning Compressor

["Christopher Ritchie" <cjr1@gte.net>]

The previous owner told you the A/C compressor clutch was seized.  
     You therefore probably need to replace it.  The compressor, that 
     is.  Clutches cost ~$125, and you need special tools to remove and 
     replace them on the compressor.  The compressor will have to come 
     out to replace the clutch.  You can get used compressors with a 
     clutch for ~$50 and rebuilt ones with a clutch and a guarantee for 
     ~$250.  New ones are $600 - $800.  Welcome to the wonderful world 
     of Audi parts prices.
     
     Before you replace it, try to test it.  There is a single wire 
     which goes to the compressor/clutch.  Look for it and its Kostal 
     (not sure of the correct nomenclature) connector on the driver's 
     side frame rail underneath and behind the fan.  Apply 12 DC volts 
     to it.  The clutch should engage.  You should see it and hear it 
     click when you apply and remove the 12vdc.  A convenient source of 
     12vdc nearby is the positive battery post jumper cable connection 
     over on the other side of the engine bay.  
     
     If the compressor/clutch is no good, you will have to replace it.  
     This is not a difficult job.  But when you replace it, you will 
     lose whatever refrigerant charge you had in the system.  You can 
     recharge with the original R-12 at 3 cans @ ~$50ea, or convert to 
     R-134a at 3 cans @ $6ea plus some other retrofit pieces.  I highly 
     recommend the R-134a for cost reasons.  Conversion is easy, but 
     that is another story.  Let me know if you are interested.