2005 Mercedes C-Class Owner's Manual - Page 182

Controls in detail Climate control i The air recirculation mode is activated automatically at high outside temperatures. The indicator lamp on the , button is not lit when the air recirculation mode is automatically switched on. After approx. 30 minutes, outside air is added to the air inside the vehicle. If you have turned off the air conditioning ( page 181) or the outside temperature is below 41°F (5°C), the air recirculation mode will not switch on automatically. Deactivating Press button , ( page 175). The indicator lamp on the button goes out. The air recirculation mode is deactivated automatically: after five minutes if the outside temperature is below approximately 41°F (5°C) after five minutes if the air conditioning is turned off after 30 minutes if the outside temperature is above approximately 41°F (5°C) At outside temperatures above 79°F (26°C) the system will not automatically switch back to outside air. A quantity of outside air is added after approximately 30 minutes. i If you keep button , pressed the side windows and tilt/sliding sunroof* will return to their previous position. 180