PURPOSE: To make possible to prevent a refrigerant gas from being overheated, by arranging a heat exchanger downstream of an exhaust pipe, and scattering a brine in the buttom of a tank over the exhaust pipe so that the heat exchange of the exhaust pipe with the heat exchanger is effected under the flow of brine drops.

CONSTITUTION: The refrigerant gas pressurized at a compressor 2 is passed via a four- way valve 6 to a condenser 3 where it is liquefied, and the liquefied gas is passed via a check valve 18 to an expansion valve 19 where the pressure of the liquefied gas is reduced, and then is introduced into an evaporator 4 where it is allowed to evaporate thereby cooling operation can be effected by the heat of evaporation. When heating is effected and if the engine temperature is low and the car heater is not so effective, heating will be effected by the operation of a heat pump of the refrigerator; that is, the refrigerant gas compressed at the compressor 2 enters the evaporator 4 via a four- way valve 6 to be cooled and liquefied, heating is effected by the heat of evaporation, and the liquefied refrigerant is passed via a by-pass pipe 21 to an expasion valve 22, and is evaporated in the heat exchanger 5. In this case, the heat of evaporation is taken out by the brine liquid that is scattered from a scattering nozzle 12 over the exhaust heat exchanger 8 and flows down on the heat exchanger 5.