Hvac Countrol Not Working

[zpainter1015]

I have a 1992 GMC c2500 with the electronic hvac controls. We were driving and the controls quit and the A/C shut off and nothing else worked. Checked fuses and were fine, drove for awhile longer and hit a bump and they started working again till I shut the truck off. Didn't work till about a week later when it came on, but the screen was flashing, going around through all the symbols. Figured the controls were messed up inside. so put a used control in and still doesn't work. I checked for power at the plug and have a constant power and a few terminals with power with key on. Maybe a ground problem? or something else?

[ryank1]

Probably a bad used part. These were a common failure and I would look for a reman and not used.