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E46 Climate Control
Rear window defroster operation (All models)
The rear window defroster is controlled via a request from the button on the panel. After
switching on for the first time, the rear window is heated for 17 minutes. Output voltage to
the window is provided by the K13 rear defogger relay.
After automatic switch off, if the button is pressed once again the control unit will provide
another 17 minutes of operation. If the vehicle voltage drops below 11.4V during this sec-
ond heating operation the function is stopped, however the LED on the button will not be
extinguished. If voltage increases past 12.2V for at least one second, operation will
resume. The control circuit of the convertible varies slightly due to the folding top.
Defroster operation specific to Convertibles
When the button is pressed on the IHKR control panel, relay K13 is energized. K13 sup-
plies KL 30 to defroster relay K99. Relay K99 is energized when the KLR is switched on
and the soft top is closed and locked to the windshield frame. This completes the circuit
and allows the rear window to be heated.
If the soft top is lowered during defroster operation, voltage to relay K99 is interrupted by
the CVM to prevent the rear window grid from heating when the top is lowered into the stor-
age compartment.
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