My 2003 Suburban has dual climate zone controls. Regardless of the setting on the passenger side, it blow out hot air. Driver side works just fine. Interesting that the light for the driver slide temperature slider is working but not for the passenger side. When I first start, it will blow cool air but will then change to hot. Does this sound like a blend door actuator problem? Or might it be the temperature slider has gone bad given that the light behind it doesn't work?

 

Found the problem. Replaced the control module.