Heated Glass Element: Description and Operation

Rear Window Defogger

How the Circuit Works
Voltage is applied at all times through fuse 53 to the rear window defogger relay contacts. With the ignition switch in ON (II), voltage is applied through fuse 3 (in the driver's under-dash fuse/relay box) to the climate control unit and the rear window defogger relay coil.

When the rear window defogger switch (in the climate control panel) is pushed once, a path to ground is provided for the rear window defogger relay coil through the climate control unit. The rear window defogger ON indicator (built into the climate control panel) comes on and the rear window defogger relay contacts close. Voltage is applied to the defogger grid on the inside surface of the rear window, and the grid heats the rear window to remove any fog from the glass.

The rear window defogger can be turned off by pushing the rear window defogger switch a second time or by turning the ignition switch to LOCK (0). A timer in the climate control unit will automatically turn the defogger off after it has been on continuously for about 15 minutes.