2008 Mercedes C-Class Owner's Manual - Page 266

Controls in detail 3-zone automatic climate control* (Canada only) Rear window defroster Warning! Activating: Switch on the ignition. Press button ¯ ( page 259). The indicator lamp in the button comes on. Any accumulation of snow and ice should be removed from the rear window before driving. Visibility could otherwise be impaired, endangering you and others. G Air recirculation mode Switch to air recirculation mode to prevent unpleasant odors from entering the vehicle from the outside (e.g. before driving through a tunnel). This setting cuts off the intake of outside air and recirculates the air in the passenger compartment. Warning! ! The rear window defroster uses a large amount of power. To keep battery drain to a minimum, switch off the defroster as soon as the rear window is clear. Deactivating: Press button ¯ ( page 259). The indicator lamp in the button goes out. i If the rear window defroster switches off too soon and the indicator lamp goes out, this indicates that too many electrical consumers are operating simultaneously and the load on the battery is reducing available voltage. The system responds automatically by deactivating the rear window defroster. G i The rear window defroster is automatically deactivated after some time of operation depending on the outside temperature. Fogged windows impair visibility, endangering you and others. If the windows begin to fog on the inside, switching off the air recirculation mode immediately should clear interior window fogging. If interior window fogging persists, make sure the air conditioning ( page 267) is activated, or press button y. 265