Abstract: The invention concerns a device comprising, additionally to the main thermostat (6) for interrupting the circulation of the refrigerant in the cooling radiator (2) to accelerate the heat engine (1) heating for a cold start, a three-way valve (10) which, when the temperature rises above the threshold opening the main thermostat (6), enables to gradually reduce the fluid flow rate in the heating radiator (3) then to cancel it so as to increase the fluid flow rate in the cooling radiator and consequently enhance the engine cooling efficiency.

Abstract: The system for managing the heat energy developed by a heat engine (10) of a motor vehicle comprises a main system (2) equipped with a main pump (12), a heat engine (10) and a main cooling radiator (18). The main system (2) furthermore comprises a short-circuit pipeline (20) and a heating pipeline (22) comprising an air heater (24), and a secondary loop (4) including a secondary radiator (60) and a secondary pump (58). The main system and the secondary loop can comprise equipments heated or cooled by equipment exchangers (34, 36, 38, 64, 66) included in the main system (2) and/or the secondary loop (4). The maim system (2) and the secondary loop (4) are connected by interconnecting means which make it possible to cause a same coolant fluid to circulate in a controlled manner between the main system and the secondary loop or to prohibit this circulation depending on the load state of the engine (10).