Vehicle air conditioning

The invention relates to a vehicle air conditioning system (1) comprising an evaporator (3) and at least a heater (4, 5) is located which in a hot air path (W), and a heater (4, 5) bypassing the cold air bypass (6), which in a cold air path (K), comprising a first flap (9a) connected between the evaporator (3) and the heater (4, 5) is arranged, and at least a second flap (9b), which behind the heater (4 , 5) is arranged wherein the second flap (9b) preventing reverse flow of tempered air into the heater (4, 5). Here, the air conditioner (1) provides in all operating positions of the flaps (9a, 9b) has a minimum opening air inflow side of the heater (4, 5), while the second flap (9b) of the hot air path (W) completely closes in cooling mode.