Heating and/or air conditioning device for vehicle compartment, with sophisticated aerothermic management

The device has an air mixing chamber (7) communicating with hot and cold air flow supply conduits (4,5) and with two air flow distribution conduits (2,3) connected with air distribution openings. A control unit has two valves (9,10) equipped with respective blocking walls (12,13) to manage passage of hot and cold air flow to the chamber, and a valve (11) managing passage of hot air flow to a downstream part (17) of the chamber.