I have a 2005 GMC Envoy. I had a battery issue that has been fixed. I am not sure if this is related or that I just noticed. 1. My headlights stay on even though there is plenty of light outside/daytime and the setting is to auto. I can manually turn off when the car is running but when back to auto they come on again. Not a big hassle.. 2. my ac runs and gets cool, however the selector switch for front, foot, both, defrost etc doesn't change. It only blows out the defrost and feet. So when I change to front blowers, or feet, etc it only blows to feet and defrost vents. the 1 through 5 settings work fine. I looked at the vaccum line on the top center of the engine and it is connected fine. Even took it off and put it back on. I don't know if the lights and ac are any way connected other than when the battery went dead and I charged it - then replaced it - I wondered if this could be an electrical issue.