If it's the front, this has happened to me and it could be the same problem. The knob on mine would get stuck and it was due to a pinched wire inside the panel that prevented the knob to be switched from heat to defrost or AC depending on where it was pinched at. The whole dash had to be taken apart to fix it. Luckily I knew someone whow could fix it for me temporarily but once I needed to turn the knob again it got stuck and I'm having the same problem once again. I have heard that it's going to cost about $200 if I take it in somewhere to have it fixed.
Wednesday, October 22nd, 2008 AT 6:56 AM