In-vehicle air conditioner

An in-vehicle air conditioner comprising:

• a refrigerant circuit for circulating a hydrocarbon refrigerant, the refrigerant circuit comprising a compressor, a condenser for heat dissipation, an expansion valve, and an evaporator for heat absorption;
• a heat exchanger which is integrally formed with the evaporator of the refrigerant circuit to cool a cooling liquid with the refrigerant contained in the evaporator;
• a cooling liquid circuit for circulating the cooling liquid, the cooling liquid circuit having a cooler core;
• and
• an air conditioning unit comprising an air passage in which the cooler core is disposed, the air conditioning unit configured to cool air passing through the air passage by the cooler core and supply the cooled air to a vehicle compartment, wherein
• the cooling liquid circuit comprises a gas-liquid separator and a relief valve;
• and
• the relief valve is disposed on a top part of the gas-liquid separator outside the vehicle compartment and is configured to open when a pressure inside the gas-liquid separator is increased.