2004 Mercedes C-Class Owner's Manual - Page 168

Controls in detail Automatic climate control* i If you keep button O pressed, the side windows and the sliding/pop-up roof* will close. i The air recirculation mode is activated automatically: at high outside temperatures if the concentration of carbon monoxide and nitrogen oxide in the outside air increases, for example in a tunnel (charcoal filter activated) Please note that the charcoal filter must be activated ( page 169) for the air recirculation mode to be activated automatically. If you have turned off the air conditioning ( page 170) or the outside temperature is below 41°F (5°C), the air recirculation mode will not switch on automatically. Deactivating Press button O ( page 163). The indicator lamp on the button goes out. i If you keep button O pressed, the side windows and the sliding/pop-up roof* will return to their previous position. 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. Warning! G Never operate the side windows and the sliding/pop-up roof* if there is the possibility of anyone being harmed by the closing procedure. In the event that the closing procedure causes potential danger, the closing of the side windows can be immediately halted by pressing or pulling the respective window switch. The closing of the sliding/pop-up roof* can be immediately halted by moving the sliding/pop-up roof* switch in the overhead control panel in any direction. The closing of the side windows and sliding/pop-up roof* can be reversed by again pressing and holding the O button. 168