88 GMC heater control problems

[ksierens]

I sometimes have problems with the heat/air coming on by it self and I am unable to shut it back off again. Well I can shut it off, but it comes back on again. After a few times, the lights go off on the control, and it will not do anything until you shut the truck off.
We have changed the control head, and I have changed the relays, but I still have the problem once in a while.

[vzfox]

Try tracing the wiring.....could possibly be a bad/loose ground wire or other wires that control the head are shorting together.

[ksierens]

Thanks, I look into it.

[ksierens]

Well I am still having problems with this and it seems like it only happens when the headlights/running lights are turned on. I don't have a wiring diagram and as old as it is I have to start pulling things apart unless I have a good idea of where the problem may be.