Heated Glass Element: Description and Operation

MANUAL

With the Ignition Switch in RUN, voltage is applied to the heater and A/C Control Assembly. When the Rear Defogger Switch is depressed, a momentary enable signal is provided for the Timer-Relay. The Timer-Relay contacts close, lighting the System ON LED and powering the Rear Defogger and Heated Mirrors. The rear window and outside mirrors become warm to remove condensation from the glass surface.
The first time the Rear Defogger Switch is pressed, the Timer-Relay allows the Rear Defogger and Heated Mirrors to operate for approximately 10 minutes. Each time the Rear Defogger Switch is pressed thereafter, the Timer-Relay resets to operate for approximately 5 minutes. The Timer-Relay resets to 10 minutes when the Ignition Switch is turned OFF, then back to RUN. The timer also shuts off any time the Rear Defogger Switch is pressed while the Rear Defogger and Heated Mirrors are already on.

ELECTRONIC

With the Ignition Switch in RUN, voltage is supplied to the Rear Defogger Relay coil. Depressing the Rear Defogger Switch signals the HVAC Programmer to provide a ground path for the Rear Defogger Relay coil. The relay energizes, closing the contact and applying voltage to the Rear Defogger and Heated Mirrors. The rear window and outside mirrors become warm to remove condensation from the glass surfaces.
The first time the Rear Defogger Switch is pressed, the Solid State Timer (in the HVAC Programmer) allows the Rear Defogger and Heated Mirrors to operate for approximately 10 minutes. Each time the Rear Defogger Switch is pressed thereafter, the Solid State Timer resets to operate for 5 minutes. The timer resets to 10 minutes when the Ignition Switch is turned OFF, then back to RUN. The timer also shuts off any time the Rear Defogger Switch is pressed while the Rear Defogger and Heated Mirrors are already on.