Description & Operation

Rear window defogger system uses an instrument panel mounted switch with an integral indicator light. Rear defogger switch and timer circuit are part of Heating Ventilation Air Conditioning (HVAC) controller. Timer circuit directs power to rear defogger grid. Standard rear window defogger system uses a heating wire grid bonded to inside of rear window. Optional rear window defogger system (models with tinted rear window) use a number of horizontal ceramic silver compound element lines and 2 vertical bus bars for heating rear window that are baked inside of the surface during window forming operation.

Ignition switch must be on to operate rear window defogger system. When rear window defogger switch is pressed, timer relay allows current to flow to grid for approximately 10 minutes, then stops current flow. Each time rear window defogger switch is activated after initial activation, timer relay will allow current flow to grid for approximately 5 minutes. If ignition is turned off then back on, timer relay resets to 10-minute cycle. Any time rear window defogger switch or ignition switch is turned off, current stops flowing to grid.

Under some operating conditions, glass may not feel warm to the touch. Switch may need to be pressed for additional cycles depending on vehicle speed, outside window temperature, atmospheric pressure and number of passengers.