Manual Blower Control

The active blower characteristic can be adjusted positively or negatively using the blower buttons + and -. The blower can be switched off by repeatedly pressing the button, whereupon OFF appears in the display. If the blower is switched off while the air-conditioning compressor is switched off, a function to deactivate the compressor protects the evaporator from icing.
In the blower-OFF mode, air distribution is set to defrost and air-recirculation and all other actuators are switched off.

Ram pressure compensation
The airflow is influenced by the ram pressure which is, in turn, dependent on the vehicle's speed. To compensate for this relationship between ram pressure and vehicle speed, the ram flap is actuated in the "closed" direction according to the driving speed > 56 MPH. The flap position is also dependent on the blower voltage.