Air conditioning device

The system has an air passage housing (9) in which a hot air duct (W), a cold air duct (K), a ventilation duct, foot space duct and a defrosting duct (D) are formed. A combined mixing and distributor flap (2) controls temperature and distribution of air. The flap is designed such that the hot and cold air ducts are completely closed in a position in which the hot and cold air ducts are completely opened. Cold air is mixed with hot air that flows through the defrosting duct in a defrosting operation in a position in which the cold air duct is completely closed by the flap.