Air conditioning unit for the passenger compartment of a vehicle

The air conditioning system for the interior of especially a streetcar has a first duct system with inlet flow openings in region of the ceiling and a second duct system with inlet flow openings in the region of the floor, connected via a regulating unit to a conditioning unit for the selective producing of a cooled or a heated airflow. The first and second duct system extend from the regulating unit via controllable flaps, the positions of which are controllable in dependence upon the outside temperature.