Abstract: A device for heating a passenger space in a power vehicle comprises a main passage for supplying air, an intermediate passage associated with the main passage and branching into side passages connected with a passenger space, a heat exchanger, a branching passage leading from the main passage over the heat exchanger, a guiding element movable between and fixable in at least two end positions for air to connect the branching passage with the main passage and to separate the former from the latter so that in a flow direction of the air the air enters behind the heat exchanger in the intermediate passage, a blowing nozzle opening in a passenger space and connected with the intermediate passage, the intermediate passage being subdivided in partial passages, one of the partial passages being connected with the blowing nozzle while the other of the partial passages merging into the side passages, the guiding element in its operative position in which it connects the branching passage with the main passage opens a c