Abstract: A vehicle air conditioning system includes a refrigerant circuit that circulates a refrigerant through a compressor, a heat-absorbing heat exchanger, a decompression unit, and a heat-dissipating heat exchanger, a heat medium circuit including a high-temperature heat medium circuit that circulates a high-temperature heat medium and a low-temperature heat medium circuit that circulates a low-temperature heat medium, a vehicle interior heat exchanger that exchanges heat between air and at least one of the high-temperature heat medium and the low-temperature heat medium, a vehicle exterior heat exchanger that exchanges heat between air and at least one of the high-temperature heat medium and the low-temperature heat medium, and a switching unit that switches respective flows of the high-temperature heat medium and the low-temperature heat medium in accordance with an operation mode of the vehicle air conditioning system.