An air-conditioning apparatus having a refrigeration cycle in which a compressor, a refrigerant flow switching device, a heat source side heat exchanger, a use side expansion device, and a use side heat exchanger are connected to one another using a refrigerant pipe, the air-conditioning apparatus comprising:
- an injection pipe having one side connected to an injection port of the compressor, and another side connected to the refrigerant pipe between the use side expansion device and the heat source side heat exchanger, the injection pipe being configured to inject a refrigerant during a compression operation of the compressor;
- a refrigerant heat exchanger configured to exchange heat between the refrigerant flowing through a refrigerant pipe in the refrigeration cycle and the refrigerant flowing through the injection pipe;
- a connecting pipe having one side connected to the refrigerant pipe between the refrigerant flow switching device and the use side heat exchanger, and another side connected to a suction side of the compressor, the connecting pipe being configured to direct part of a discharge refrigerant from the compressor to the heat source side heat exchanger and then to cause the part of the discharge refrigerant to flow into the suction side of the compressor;
- an opening and closing device disposed in the connecting pipe and capable of switching between opening and closing of a passage in the connecting pipe;
- a first temperature sensor configured to detect a temperature on a discharge side of the compressor;
- and
- a controller configured to switch the opening and closing device in accordance with a detection result of the first temperature sensor,
- wherein the controller is configured to perform
- a low-outside-temperature heating operation start-up mode when an outside temperature is a predetermined low temperature in a case where the detection result of the first temperature sensor is greater than or equal to a preset first predetermined value, and
- a low-outside-temperature heating operation mode after performing the low-outside-temperature heating operation start-up mode,
- wherein during the low-outside-temperature heating operation start-up mode,
- the opening and closing device is opened,
- a part of the refrigerant discharged from the compressor flows into the use side heat exchanger,
- a part of the refrigerant flowing out from the use side heat exchanger flows into the injection port of the compressor via the injection pipe,
- a rest of the refrigerant discharged from the compressor flows into a suction side of the compressor via the connecting pipe, and
- wherein during the low-outside-temperature heating operation mode,
- the opening and closing device is closed,
- the refrigerant discharged from the compressor flows into the use side heat exchanger,
- the part of the refrigerant flowing out from the use side heat exchanger flows into the injection port of the compressor via the injection pipe.