86 CD Quattro A/C Temperature Control

["Colin Barfoot" <Colin_Barfoot@msn.com>]

My Auto temperature control doesn't anymore, either on "Econo" or on "auto" 
"Lo" or "high". 
(temperatures below are in Celcius 21~=70 Farenheit Celcius *9/5+32 = 
Farenheight.
The symptoms developed at first as just having to set the setpoint a few 
degrees cooler than actual. For example putting the setpoint at 18 or 19 to 
get 20-21.
Now setting it even at 18 will eventually get the car up to 25 or so.
One thought was that either the interior sensor or the sensor fan motor has 
gone kaput.
Any suggestions?
Is it possible that just too much dust got sucked in over the winter?

Also before this occured the warm air to the feet just didn't seem to work, no 
matter how warm the air or coolant was it wouldn't blow at the feet.
Are these problems related or is the second more related to the mysterious 
damper motor  cable system?
TIA
Colin
86 5000CD Quattro awaiting head(no driving gives time to think about those 
niggling little problems...)