Heat exchanger and vehicle heating or air conditioning device comprising such a heat exchanger

The heat exchanger in plate-form construction has a first flow passage (16) for a first flow medium located between plates (12,14) forming a plate pair (13), and several second parallel-connected flow passages (18) for a second flow medium each between two plate pairs. The second parallel-connected flow passages are formed by the respective plates of adjacent plate pairs. The second flow passages have a curved progression so that the second medium while flowing through the heat exchanger experience a change in flow direction. Independent claims are included for a heating or air conditioning system for a motor vehicle, incorporating the aforesaid heat exchanger, and for an air conditioning system in which the heat exchanger is equipped with an evaporator.