I just had the thermosat replaced earlier this year. It warms up pretty fast. In the past, the unit (AC Light) would come on, but the fan wouldn't blow until the car warmed up. Now the AC Light won't even come on (stays in off position). Took about 30 minutes, then the AC (green light) and FAN kicked in. The tech told me that this is the sign of a faulty sensor, he just doesn't know which one, since there was nothing in the computer. Of course the weather is getting warmer again, so won't see the problem for a while.