Air conditioner for vehicle

An air conditioner for a vehicle that supplies air into the vehicle compartment, the air conditioner comprising:

• a compressor that has
• a suction port that draws a low-pressure refrigerant,
• a compression mechanism that compresses the low-pressure refrigerant to be a high-pressure refrigerant,
• a discharge port that discharges the high-pressure refrigerant,
• an intermediate port that draws an intermediate-pressure refrigerant from a cycle and guides the intermediate-pressure refrigerant to flow into the compression mechanism and join a refrigerant being compressed in the compression mechanism, and
• an electric motor that operates the compression mechanism;
• a radiator that performs a heat exchange between the air and the high-pressure refrigerant discharged by the discharge port and makes the high-pressure refrigerant to radiate heat;
• a first pressure reducer that reduces a pressure of refrigerant flowing out of the radiator to be the intermediate-pressure refrigerant;
• a gas-liquid separator that separates the intermediate-pressure refrigerant, which flows from the first pressure reducer, into a gas-phase refrigerant and a liquid-phase refrigerant;
• a second pressure reducer that reduces a pressure of the liquid-phase refrigerant separated in the gas-liquid separator to be the low-pressure refrigerant;
• an exterior heat exchanger that performs a heat exchange between an outside air from an outside the vehicle compartment and the refrigerant flowing out of the second pressure reducer and evaporates the refrigerant;
• an intermediate-pressure refrigerant passage that guides the gas-phase refrigerant separated in the gas-liquid separator to flow to the intermediate port;
• a switching device that switches between
• a refrigerant circuit of a two-stage compression mode that guides the intermediate-pressure refrigerant to the intermediate port and
• a refrigerant circuit of a single-stage compression mode that blocks at least a flow of the intermediate-pressure refrigerant into the intermediate-pressure refrigerant passage and guides the refrigerant remaining in the intermediate-pressure refrigerant passage to flow out of the intermediate-pressure refrigerant passage;
• and
• a controller that controls the compressor and the switching device, wherein
• the controller, when receiving a compressor stop signal that requests to stop the compressor in the two-stage compression mode,
• operates the switching device to switch from the refrigerant circuit of the two-stage compression mode to the refrigerant circuit of the single-stage compression mode,
• operates the compressor in the single-stage compression mode for a specified time and then stops the compressor, and
• restarts the compressor when the compressor stop signal is canceled.