Without dynamic pressure compensation, as the driving speed increases, the air volume at the air inlet ducts also increases disproportionately. This effect is compensated in that the fresh air/recirculating air flap reduces the cross section of the air inlet duct dependent on the vehicle speed. The fresh air/recirculating air flap is not adjusted for short changes in the driving speed. For this reason, the set position is calculated from the speed signal with a hysteresis (delay). The vehicle speed information is made available via the K-bus from the instrument cluster.
The fresh air/recirculating air flap reduces the opening angle within a certain speed range according to an empirically defined characteristic curve.