My heater control/ac control seems not to be working. I can only have the heat at the highest temp. and at the highest fan speed. That also happens in the summer with ac. The previous owner talked about it was a temp. sensor that failed and you just had to duct tape it one way or the other. Any suggestions?

 

I'd start by reading the heat & AC section of the 89-91 manuals.

It's at the link in my sig.

 

Its common for the Logicon to stop woring.
Contact "IceMark" He fixes them.
-a

 

remove everything behind the dash.............

 

Icemark is your man. Superb work, very reasonable prices.