A heating, ventilation and air-conditioning unit for the passenger compartment of a motor vehicle

A unit includes a support structure (2) with first and second intakes (3, 4) defined therein for air from inside and outside the compartment respectively, and at least one outlet (5-7) for conveying air treated in the unit (1) into the passenger compartment, a fan (10), arranged downstream of the said intakes (3, 4) for setting up a flow of air through the structure (2) between one of the said intakes (3, 4) and at least one outlet (5-7) ; first and second heat exchangers (13, 14) arranged downstream of the fan (10) for respectively cooling and heating the flow of air set up by the fan (10) ; an air heater (30) integrated into the support structure (2), including a fuel burner (31) and having an intake (32) for combustion air which is in communication with the second intake (4) of the unit (1) and an outlet (33) for evacuation of the combustion gases; the air heater (30) being arranged so that it can heat a flow of air set up by the fan (10) between a first intake (3) and at least one outlet (5-7) of the unit (1); and an electronic control unit (ECU) connected to sensors (18, 19) and actuators (15-17;...) associated with the unit (1), to a control device operable by a user and to the said burner (31), and arranged to control operation of the unit (1) of the burner (31) in predetermined modes.