4k/CGT/Urq owners! Get you A/C ICE cold!!! (long)

[David]

Well, this is definitely one for the archives. Are you a 4000, Coupe GT or Urq owner who is frustrated by your A/C system? Does it take forever to get cold? Or never gets REALLY cold despite being in perfect working order? Well, there's the anser! Adjust your A/C temperature sensor! My CGT was converted to R134a. I have no idea how well it worked with R12 as the AC was dead when I got the car, but with R134a on a hot sunny day, it took at least 10 minutes for vent temps to get down to even 60*F, sometime longer. It would bottom out around 50*F after about 1/2 hour, and if you stopped the engine for more than a minute or two it would take for ever to get cold again. The system was in perfect order with proper pressures. I had just fgured that this was the price for admission to the R134a crowd. Boy was I wrong, a quick adjustment of the AC temp sensor an it works like it should have all along. Now, on a bright sunny day, vent temps hit 56*F within 3 minutes, 50*F within 4, and it bottoms out at 40*F in city driving and 38*F on the highway in less than 10 minutes! So I figiured I'd better pass this along with instructions (care of Todd Miller on AudiWorld):

The temp sensor is just to the right of the evaporator.  So, remove the glove box to get to it. Remove the 14mm nut that holds it to the bracket and then CAREFULLY move the temp sensor and the capilary tube forward till you can see the top of it.

There is a small phillips head screw on the top, this is the adjustment screw. Mark that screw and the body of the sensor for where they are at as a reference.  Now turn it counter clock-wise to lower the tempurature at which it kicks out the compressor.  Use 1/4 turn inrcrements and go for a drive after each one to make sure the vent temps don't go too low (causing evaporator to freeze. Use a calibrated thermometer in your air vents to accurately check the tempurature.

Some people on AW have reported that their sensor only needed 1/4-1/2 turn, mine OTOH needed a full 2 turns, so YMMV. Anyway, this was WELL worth the time it took to do this. Oh, just wondering, what terrible things happen if the evaporator does freeze over? I didn't have any way to get a therometer probe into or behind the evaporator, so it COULD be frosting up during the compression cycle, assuming that the vent temps vary greatly from the evap temp (which IMHO is quite possible on these systems).

TIA,

Dave
1987 CGT Special Build 2.3
SE Virginia