I have had my HHR in 2 times for this problem. When I turn on the heat (or AC) and want to turn it off it will stick on high and not turn off , or turn on by itself, and I have to end up adjusting the temp to keep it comfortable. The first time I had it in they had to replace a fried resistor, after I picked it up the problem continued. Now it will not turn on by itself but if I turn it on it will not go off until it is parked for a while. I took it in Monday since I am off this week, and I guess they could not find anything and contacted GM tech and they attributed it to an afterblow option that was probably turned on when I had it in the first time. They said they could turn it off if I wanted, I said no and am now wondering if I should have said yes to rule that theory out. I have looked into this "afterblow" feature and it seems like it is something that occurs when the vehicle is off, the AC is being used, and it is at least 70 degrees--none of which fit my conditions. Has anyone else had this problem? If so what was the fix. Or does anyone know if it is easy to disable this feature or if I need to go to the dealer. Thanks for any info.