Coupe quattro climate control weirdness

Joshua Van Tol josh at
Mon Jan 19 23:17:21 EST 2004


It sure sounds like the feedback strip in the temperature control servo 
is shot. You might be able to disassemble the servo and adjust the 
potentiometer to run on a non-worn spot of the resistance track, or you 
could just replace it. Alternately, there was a mod for this type of 
problems on the earlier automatic climate control systems in the 5k 
series cars that involved soldering a 680k resistor from the wiper of 
the feedback strip to one side or the other. The same mod might work 
here. Check there's probably some climate 
control info there.
On Jan 18, 2004, at 1:48 PM, Horning, Zain A wrote:

> Hi all,
> I have a 1990 Coupe quattro that has been experiencing some climate 
> control issues.  Before I start spending money, I thought I would see 
> if anyone can confirm my suspicions.
> Last winter, my climate control would occasionally "get stuck" and 
> blow hot air constantly, regardless of the setting.  The problem 
> seemed to go away during the spring and summer so I forgot about it.  
> This winter, the problem is back with a new twist.  Sometimes it will 
> stick on a blazing hot setting and other times it will stay on a cold 
> setting.  However, usually after driving the car for a little while 
> the climate control will start functioning normally.  I checked for 
> system errors and sometimes the climate control display will show 
> error "15".  Bentley seems to suggest that the servo located in the 
> bottom, center of the dash is as fault.  I believe that this servo 
> controls a flap that mixes hot and cold air so it would make sense 
> that it is my problem.  Before I tear apart my dash and buy a new 
> servo, can anyone confirm that they have had a similar 
> problem/solution?
> Thanks in advance, Zain Horning
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