Coupe quattro climate control weirdness

[Horning, Zain A]

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