Description And Operation

Description 

In the case of poor visibility or frost, the rear window and door mirror defroster can be switched on by pressing the button on the A/C Heater Control. The nozzles of the windshield washer and the upper part of the windshield are also heated. The heating resistances for these components absorb a considerable amount of energy and are therefore controlled and deactivated after a certain period of operation. The defrosting is timed according to a logic managed by the Body Control Module (BCM) and the resistors stay powered for no longer than 20 minutes and then power is interrupted.

The power supply is cut off in the following conditions:

• Key function in STOP position.
• Off signal from the Ignition switch.
• Battery voltage below 11.5 V.
• After the first 10 minutes of operation if the engine speed is below 960 RPM.

With the defroster on, the warning light next to the control button also comes on. The activation timer (20 minutes) is set again each time the button is operated. The rear window, windshield washer nozzles and door mirror defroster circuit is controlled by a dedicated relay and protected by two fuses located in the rear Power Distribution center (PDC).

Operation 

The heated rear window relay is located in the rear PDC. It controls the energizing of the rear window defrosting grids and is protected by a fuse in the rear PDC. The same relay controls the energizing of the defroster for the door mirrors via the circuit protected by a fuse in the rear PDC. At this same time, it also controls the defroster in the windshield washers. The coil for the relay is supplied by the ignition power supply circuit protected by a fuse in the BCM.

Relay switch is energized by a ground from the BCM; this signal is sent on the basis of the control logic and in the defrosting command from the HVAC module via the Controller Area Network (CAN). Also the rear window activation signal is sent from the A/C Heater Control to the BCM via CAN, and the "defroster ON" warning light signal is sent by the HVAC module. The BCM receives direct battery power via the circuit protected by a maxi fuse in the battery distribution unit on the battery. The BCM receives an ignition power supply by the signal coming from the Radio Frequency Hub Module (RFHM).