Vehicle air conditioning system and vehicle air conditioning method

A vehicle air conditioning system comprising:

• a refrigerant circuit configured to circulate a refrigerant through a compressor, a heat-absorbing heat exchanger, a decompression unit, and a heat-dissipating heat exchanger in accordance with a refrigeration cycle;
• a heat medium circuit including a high-temperature heat medium circuit configured to circulate a high-temperature heat medium that absorbs heat from the refrigerant in the heat-absorbing heat exchanger and a low-temperature heat medium circuit configured to circulate a low-temperature heat medium that dissipates heat to the refrigerant in the heat-dissipating heat exchanger;
• a vehicle interior heat exchanger configured to exchange heat between air and at least one of the high-temperature heat medium and the low-temperature heat medium;
• a vehicle exterior heat exchanger configured to exchange heat between air and at least one of the high-temperature heat medium and the low-temperature heat medium;
• and
• a switching unit configured to switch 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, wherein
• the heat medium circuit supplies the high-temperature heat medium to at least one of the vehicle interior heat exchanger and the vehicle exterior heat exchanger and supplies the low-temperature heat medium to at least one of the vehicle interior heat exchanger and the vehicle exterior heat exchanger, in accordance with the operation mode,
• at least one of the vehicle interior heat exchanger and the vehicle exterior heat exchanger includes a first heat exchanger and a second heat exchanger, the first heat exchanger and the second heat exchanger being connectable in series or in parallel in the heat medium circuit, and
• the switching unit switches a flow of the high-temperature heat medium on an upstream side and a downstream side of the heat-absorbing heat exchanger, switches a flow of the low-temperature heat medium on an upstream side and a downstream side of the heat-dissipating heat exchanger, and switches a connection of the first heat exchanger and the second heat exchanger between series connection and parallel connection.