1997 Chevrolet C1500 Silverado. When the headlights are switched on, the climate controls become inoperative (well at least the temp and location switches do, the fan control still works) AND the heat is on full blast and cannot be turn off until the headlights are turned off. And, here is a really screwy part....if you dim the instrument panel lights, while the headlights are on, then the climate control panel goes back to working fine.

Less than two years ago, had this same issue while a new transmission was being put in the truck, and just mentioned it to the mechanic. He said I needed a new climate control assembly......it was replaced with a new AC Delco version and things did indeed work fine. So, I am "guessing" that is what the problem is now, but it is hard to believe the new unit has failed so soon, and was thinking there might be something else wrong that is causing it to fail....if it did.

Any suggestions would be greatly appreciated.

Thanks, Jim

 

Bueller? Bueller?

 

Could this be a short or something like that needs to be traced?

 

Welcome to the forum. It could be anything on a vehicle that old. Get a hold of wiring diagrams (local library, repair manuals, etc.) and then go over affected circuits, I guess.