OPERATION METHOD OF HEAT PUMP-TYPE VEHICLE AIR CONDITIONING SYSTEM

The disclosed operation method of a heat pump-type vehicle air conditioning system (10) involves a step for setting a cold operating mode for raising the output air temperature of the air conditioner by means of a heater (26) or a normal operating mode for raising the heating COP; a step for detecting the temperatures inside and outside the vehicle; and a step which, by selecting either the cold operating mode or the normal operating mode on the basis of the detected temperatures inside and outside of the vehicle, is for bypassing a condenser (32), controlling the opening of an electronic expansion valve (43) contained in a bypass unit (40) connected in series to a gas/liquid separating liquid coolant storage unit (34) downstream of the aforementioned heater (26), and adjusting the pressure drop applied to the coolant.