1991 Stealth Automatic HVAC controller acting really weird!

[ulose]

Hey guys,

My 1991 Stealth RT has an issue with the auto AC unit. When you adjust the temperature up, it automatically goes right back down to the lowest temperature. I can adjust it manually all the way to 80 degrees, hold the temperature up button and the temperature will get hot coming out the vents, but when I release the temperature button it beeps its way all the way back down to 65. Ive disconnected the battery for days trying to reset everything, Ive pulled the temp unit out and disconnected it and put it back. Ive read a ton of posts, but never seen anyone describe the same problem. Anyone have any ideas?

Thanks in advance!

[DrGonzo]

Those units are known to have problems. They have the same leaking capacitor issues that all of the other computers in the car do and when that happens it can cause all sorts of weird things to occur. My guess is you have a trace on the board damaged or something that is activating the down button control.

[ulose]

DrGonzo,

Do you think I can get away with just replacing the controller, or would I need to replace the computer for the HVAC too?

[DrGonzo]

The digital display you see is nothing more than the button controls. The brain is the black box behind it. I have never seem them go bad. The display/button unit you can replace but you can still have the same issues with it all over again down the road.