I have owned my 96 Buick Skylark for five years and the heat has always been fine! The other day, I replaced the 02 sensor in the car... then the heat stopped working. I don't think the 2 are related, but maybe someone knows more about that than me. The heat sounds like it's turning on, and the vents are warm, but nothing is coming out. It kicked on out of the blue a few days ago, then just yesterday, stopped working again. Maybe the fan?? Someone help! Thanks 