First, my AC started acting funny. Then, my heater stopped working. Finally, I could hear the fan running, but no air was blowing out the vents. So I reluctantly dug into the mode switch for a second time, after just rebuilding it less than 3 years ago. Turns out, the four little nubs on the back of the rubber piece had broken off, so the thing was just randomly spinning around whenever I'd use the switch. I used some weatherstrip glue to glue the rubber piece back in place. Everything seems to be working now. Of course I had to replace a couple of fuses that blew in the process of making the repair, because I got in a hurry and didn't disconnect the battery.