Rear Window Defrost

Glass, Frames and Mechanisms

Principles of Operation

Rear Window Defrost

For MKZ the rear window defrost switch is integral to the Front Controls Interface Module (FCIM). For Fusion/Milan, the rear window defrost switch is integral to the HVAC module or the FCIM if equipped with navigation system. When the rear window defrost switch is pressed, the HVAC module will activate the rear window defrost relay located in the Battery Junction Box (BJB). When the rear window defrost relay is active, the rear window defrost grid will be energized.

The HVAC module will deactivate the rear window defrost relay when one of the following conditions is met:

- The rear window defrost switch is pressed when the feature is active
- Ignition switch state is changed from RUN to OFF/LOCK
- The 10-minute timer completes