Motor vehicle air conditioner

The air conditioning system has a housing comprising an air duct, a blower and a heat exchanger (1) that are provided in preset manner. A heat exchanger is used as refrigerant condenser (2) of refrigerant circuit for heating the interior of the vehicle during heat pump mode and for cooling the interior of the vehicle during cooling mode. The refrigerant condenser has cooling pipes (3) for passing a refrigerant. Two collecting tubes (6) are in fluid connection with cooling tubes.