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

[Roa, Greg]

Well, I have been watching this on the Audiworld forums since I saw David mention it here, and had been meaning to do this.  After he mentioned that it worked out well for him, I thought I'd give it a shot.

I took my glovebox out last night, and gave the screw a half turn.  My temps had been around 51 or so, after a few minutes (134a converted, new dryer, exp valve, and a compressor I resealed).  With a half turn, my vent temps dropped to about 48.
Went back and gave it another 3/4 turn.  Went for a drive then, and my vent temps were fluctuating between 38 and 41 degrees.  I was tempted to leave it there, but the compressor was running at nearly 100% duty cycle during lower speed driving, so I backed it out a bit.  I've now got temps hanging around 45 degrees, which makes the car nice and chilly.

I had figured something wasn't right as my compressor would run for about 20 seconds, and stay off for 45 seconds or more, even when starting to cool down.  Now, it tends to run much longer after starting the A/C, making cooldown take much less time.

More testing will follow this afternoon, as temps are supposed to be around 93F, and humid here.  To note, I was driving around 40mph, through varying terrain after adjusting the car, and cooldown was very quick.  Didn't measure how long it took to attain max cooling, but I'll do that today, using highway driving on the trip home from work.

I'm kind of suprised that the bentley makes no mention of this adjustment screw in the sections devoted to A/C.   Good tip, and well worth the time it takes to do.

Good Luck!
Greg Roa
Cincinnati, OH
86' 4kcsq  <<  Needs a front leather seat bottom.  Got one?
93' 90 CS
83' 944


>From: David <duandcc_forums at cox.net>
>To: quattro at audifans.com
>Subject: 4k/CGT/Urq owners! Get you A/C ICE cold!!! (long)
>Date: Mon, 23 Jun 2003 8:26:36 -0400
>
>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? We=
>ll, there's the anser! Adjust your A/C temperature sensor! My CGT was conve=
>rted to R134a. I have no idea how well it worked with R12 as the AC was dea=
>d when I got the car, but with R134a on a hot sunny day, it took at least 1=
>0 minutes for vent temps to get down to even 60*F, sometime longer. It woul=
>d bottom out around 50*F after about 1/2 hour, and if you stopped the engin=
>e for more than a minute or two it would take for ever to get cold again. T=
>he system was in perfect order with proper pressures. I had just fgured tha=
>t this was the price for admission to the R134a crowd. Boy was I wrong, a q=
>uick adjustment of the AC temp sensor an it works like it should have all a=
>long. 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 high=
>way 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 glo=
>ve box to get to it. Remove the 14mm nut that holds it to the bracket and t=
>hen CAREFULLY move the temp sensor and the capilary tube forward till you c=
>an see the top of it.
>
>There is a small phillips head screw on the top, this is the adjustment scr=
>ew. Mark that screw and the body of the sensor for where they are at as a r=
>eference.  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 evapor=
>ator to freeze. Use a calibrated thermometer in your air vents to accuratel=
>y 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