Mercedes-Benz 2005 C 230 Kompressor Operator's Manual page 172

Controls in detail
Good visibility
!
If the rear window defroster switches
off too soon and the indicator lamp
starts flashing, this means that too
many electrical consumers are operat-
ing simultaneously and there is insuffi-
cient voltage in the battery. The system
responds automatically by deactivating
the rear window defroster.
As soon as the battery has sufficient
voltage, the rear window defroster
automatically turns itself back on.
171