Control device for a heating and/or air conditioning unit

Control device for controlling air streams in heating and air-conditioning systems of motor vehicles comprises a frame inserted in the heating or air-conditioning system, and control devices in the form of roller blinds (2) for changing the cross-section of the air flow passage within the frame. The frame is a cassette (1) with a drive shaft (6) and a deviating shaft (7) for guiding the roller blind. The roller blind is a continuous belt with cut-outs (10) for releasing the cross-section of the passage. The drive shaft has teeth which engage in perforations (17, 18) in the roller belt. The housing (3), side parts (8), drive and deviating shafts are made of plastic and are joined together by clips to form a unit.