Device and method for controlling the air flow in a vehicle air conditioning system

The device has an air circulation housing (2) with an air duct (3) to admit fresh air and an air duct (4) for the operation with circulating air, to be united and a common air duct (10). A flap (9) regulates an opening (3') of the air duct for allowing fresh air and or a flap for the regulation of an opening (4') of the air duct (4) for the operation with circulating air. A device (12) is provided for the reduction of the volumetric air flow and formed by a flap. The flap reduces the cross section of the common air duct. The flap has a spring and arranged before a blower. An independent claim is included for a method for controlling the air flow in a vehicle air conditioning system.