There are three positions on the horizontal lever control on the left side. OFF, AIR, and FAN. When the slide is on the left, where OFF is, the fan is running, albeit at a fairly slow speed. Moving to the AIR position causes no change in the fan speed. Moving to the FAN position kicks in another fan motor, deeper in tone and with some heat (the car was parked, and hadn't been driven for about 2 hours). This second fan motor sounds like it came from the back area.