Rear Window Defogger System Description - Control/Function

The Timer Function (With HVAC Control)

The rear window defogger provides the timer control function that is controlled by the HVAC control unit. The timer control is operated by turning the vehicle to the ON mode, then turn on the rear window defogger switch. The timer operating time varies according to ambient temperature. If the rear window defogger switch is turned on when the timer is active, it toggles between ON and OFF every time the switch is pressed.

Timer operation time is changed under the following conditions:

	When the evaporator temperature sensor temperature is lower than 18 °F (-8 °C), the timer operation time is unlimited.
	When the evaporator temperature sensor temperature is higher than 20 °F (-7 °C), the timer operation time is 20 minutes. But when it was lower than 18 °F (-8 °C) once, the operation time is changed to unlimited.
	When the evaporator temperature sensor is failure, the timer operation time is 20 minutes.

The Timer Function (With Climate Control)

The rear window defogger provides the timer control function that is controlled by the climate control unit. The timer control is operated by turning the vehicle to the ON mode, then turn on the rear window defogger switch. The timer operating time varies according to ambient temperature. If the rear window defogger switch is turned on when the timer is active, it toggles between ON and OFF every time the switch is pressed.
If the outside air temperature sensor is failure, the timer operation time is unlimited.