VEHICULAR AIR CONDITIONING SYSTEM

Provided is a vehicle air-conditioning system configured so that air-cooling/heating can be efficiently performed. The system () includes a vapor compression heat pump unit (HP) having at least a compressor (CP), a condenser (CD), an expansion mechanism (EX), and an evaporator (EV) on a refrigerant circuit (RC), a brine flow path network (BC) having multiple pumps (PC, PH) and multiple flow path switching valves (TV to TV, V to V), and a vehicle indoor air-conditioning unit (AC) having an air duct (AD) and multiple vehicle indoor heat exchangers (HXC, HXC) arranged in series in the air duct. Upon actuation in an air-cooling mode or an air-heating mode accompanied by neither dehumidification nor defrosting, brine flows in series in the multiple vehicle indoor heat exchangers.