Air-conditioning apparatus

An air-conditioning apparatus comprising:

• a four-way valve having a first port, a second port, a third port, and a fourth port;
• a first three-way valve and a second three-way valve each having a fifth port, a sixth port, a seventh port, and an eighth port, the eighth port being closed;
• a compressor having a discharge portion connected to the first port and a suction portion connected to the second port and the sixth ports of the first and second three-way valves, the compressor being configured to suck refrigerant, compress the refrigerant, and discharge the compressed refrigerant;
• an indoor heat exchanger connected to the fourth port and configured to exchange heat between the refrigerant and indoor air;
• an expansion valve connected to the indoor heat exchanger and configured to reduce a pressure of the refrigerant;
• a first outdoor heat exchanger disposed between the expansion valve and the seventh port of the first three-way valve, the first outdoor heat exchanger being configured to exchange heat between the refrigerant and outdoor air;
• a second outdoor heat exchanger disposed between the expansion valve and the seventh port of the second three-way valve, the second outdoor heat exchanger being configured to exchange heat between the refrigerant and the outdoor air;
• a bypass expansion valve disposed between the discharge portion of the compressor and the fifth ports of the first and second three-way valves;
• a check valve having a first end connected to the third port and a second end connected between the bypass expansion valve and the fifth ports of the first and second three-way valves, the check valve being configured to allow the refrigerant to flow in a direction from the first end to the second end and block the refrigerant from flowing in an opposite direction therefrom;
• a discharge temperature sensor configured to measure a discharge temperature of the refrigerant discharged from the compressor;
• an indoor pipe temperature sensor configured to measure a pipe temperature of a pipe through which the refrigerant flows in the indoor heat exchanger;
• an indoor temperature sensor configured to measure an indoor temperature being a temperature of the indoor air;
• a current sensor configured to measure a current value of a current supplied to the compressor;
• and
• a controller configured to detect a switching failure at the four-way valve, the first three-way valve, and the second three-way valve,
• the air-conditioning apparatus being capable of performing
• a heating operation in which the first and second outdoor heat exchangers operate as evaporators and the indoor heat exchanger operates as a condenser,
• a defrosting operation and a cooling operation in each of which the first and second outdoor heat exchangers operate as condensers, and
• a heating-defrosting simultaneous operation in which one of the first and second outdoor heat exchangers operates as an evaporator and an other one of the first and second outdoor heat exchangers and the indoor heat exchanger operate as condensers,
• wherein the controller is configured to detect the switching failure at the four-way valve, the first three-way valve, or the second three-way valve by using the temperatures measured by the discharge temperature sensor, the indoor pipe temperature sensor, and the indoor temperature sensor and the current value measured by the current sensor in consideration of an operation status.