I have recently purchased a 2000 Grand Prix and have been driving it about a week. Yesterday on my way to work I had the heater on and it had been on for nearly an hour when suddenly every window in the car fogged up. I think it is suddenly blowing out moisture rich heat and Im not sure why. I thought about a leaking heater core but what is confusing to me is that it did it again on the way home that evening. I pulled the car over and shut the engine off. A few seconds later I started the engine and continued home and the foggy windows went away. Anyone have a clue if there is a switch or relay that might have reset when I shut it off and how I may fix the problem? The car does not run hot at all so far.
