My in-laws gave us this truck when they retired from long distance trailering vacations for medical reasons. Truck is in very good condition with 72K miles. The only current problem is an in-op A/C system. I plugged my new Actron scanner and discovered that the A/C Request if "OFF" even when the the A/C switch is pressed and the A/C lights up on the HVAC display. I don't have a wiring diagram for the truck, but I figure this has happened before and is a bad relay or something. One post I did find with a Google search indicated that it could be a bad A/C display module on the dash.

Any advice on where to look for some help? What would be geat would be a forum like this on later model GMC trucks, I found a few on older trucks, but I got rid of our '64 in '99. That old V-6 engine was huge, and at times a pain to maintain, but it never had the power of this V-8. Seems most owners of 92 pickups have a smaller V-8, but even then the HVAC wiring should be the same. May have to join a performance site for info on the V-8.
-sp4149

Try http://www.fullsizechevy.com/forums/ Good luck

First thing you generally wanna try is either charging the system, or replacing the programmer for it with a junkyard unit.

I'm assuming it does nothing when you press the A/C button right?