Rear Window Defroster (IHKA Integrated Automatic Heating/Air Conditioning)

Rear Window Defroster

Rear window defroster

Defrosting phase:
After switching on the ignition, the rear-window defroster is switched on when operated for the first time for 10 minutes or 17 minutes depending on the coding. Undervoltage monitoring is not active during this period of time.

Post-heating phase:
The post-heating phase starts up if the rear-window defroster is activated once again after initial switch-on. Clocked operation of the post-heating phase switches the voltage supply for the rear-window defroster relay at alternating intervals of 40 seconds ON and 80 seconds OFF.

Undervoltage monitoring:
Undervoltage cut-out is active during the post-heating phase. The terminal 30 voltage is evaluated in the control unit and the relay for the rear-window defroster is switched off if the voltage drops below 11.4 V. The time counter is stopped. The function indicator, however, does not go out. The relay for the rear-window defroster is switched on again if the terminal 30 voltage reaches a value above 12.2 V. For this purpose, the threshold value must be applied for at least 1 second.