The mirror defogger is controlled by the climate control unit. When the vehicle is in the ON mode and the rear window defogger/mirror defogger switch is pressed, the climate control unit sends the defogger ON signal as a B-CAN signal to the power window master switch. The power window master switch operates the driver's side mirror defogger, and sends the defogger ON signal via the LIN to the front passenger's power window switch to operate the passenger's side mirror defogger.

When the power window master switch receives a signal that the outside air temperature is 41 °F (5 °C) or below from the outside air temperature sensor, the power window master switch automatically turns on the left and right mirror defoggers within 10 seconds after the vehicle is turned to the ON mode. The mirror defogger output automatically stops in 10 minutes as a result of its timer. If the power window master switch receives a rear window defogger/mirror defogger switch input signal from the climate control unit during power mirror defogger output, the power window master switch shuts off the auto operation function immediately.