Over time, the contacts behind the switches and knobs get dirty, resulting in intermittent AC function. This can be fixed without replacing the panel by removing it and cleaning the contacts: http://www.imcool.com/articles/aircondition/AC_ControllersAreRepairable.pdf My mom told me that the AC button is intermittent on her 04 Malibu Classic (it's control panel is interchangeable with the previous Malibus, I have no idea if it's different internally) so I will try cleaning it with Caig Labs Deoxit D5 . (I once sprayed that stuff into a noisy volume control on a cheap clock radio. That was almost 10 years ago. The problem hasn't come back. I also used it on the intermittent cruise control switches on my '88 Mustang GT. It fixed them. It also fixed the intermittent buttons on my cellphone. This stuff is amazing).