An air-conditioning apparatus comprising: - a refrigerant circuit in which a compressor, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger are connected in sequence by a pipe, and configured to allow refrigerant to cycle through the refrigerant circuit; - an outdoor fan configured to send air to the outdoor heat exchanger; an outdoor air temperature sensor configured to measure a temperature of outside air; - an indoor heat exchanger intermediate temperature sensor configured to measure a temperature of refrigerant flowing through an intermediate portion of the indoor heat exchanger; - an indoor heat exchanger outlet temperature sensor configured to measure a temperature of refrigerant flowing through an outlet of the indoor heat exchanger; and - a controller configured to, when a measured value from the outdoor air temperature sensor is equal to or less than a predetermined value, perform a low-outside-air-temperature cooling operation mode, characterised in that in the low-outside-air-temperature cooling operation mode, the controller is configured to reduce a rotation speed of the outdoor fan, and to, when a difference between a measured value from the indoor heat exchanger outlet temperature sensor and a measured value from the indoor heat exchanger intermediate temperature sensor is equal to or greater than a first threshold, increase an opening degree of the pressure reducing device, the air-conditioning apparatus further comprising an indoor temperature sensor configured to measure an indoor temperature, wherein in the low-outside-air-temperature cooling operation mode, the controller is configured to, when the difference between the measured value from the indoor heat exchanger outlet temperature sensor and the measured value from the indoor heat exchanger intermediate temperature sensor is equal to or greater than the first threshold and a difference between the measured value from the indoor heat exchanger outlet temperature sensor and a measured value from the indoor temperature sensor is equal to or less than a third threshold, increase the opening degree of the pressure reducing device, wherein in the low-outside-air-temperature cooling operation mode, the controller is configured to, when the difference between the measured value from the indoor heat exchanger outlet temperature sensor and the measured value from the indoor heat exchanger intermediate temperature sensor is less than a second threshold, which is smaller than the first threshold, and the difference between the measured value from the indoor heat exchanger outlet temperature sensor and the measured value from the indoor temperature sensor is greater than the third threshold, decrease the opening degree of the pressure reducing device. - a refrigerant circuit in which a compressor, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger are connected in sequence by a pipe, and configured to allow refrigerant to cycle through the refrigerant circuit; - an outdoor fan configured to send air to the outdoor heat exchanger; an outdoor air temperature sensor configured to measure a temperature of outside air; - an indoor heat exchanger intermediate temperature sensor configured to measure a temperature of refrigerant flowing through an intermediate portion of the indoor heat exchanger; - an indoor heat exchanger outlet temperature sensor configured to measure a temperature of refrigerant flowing through an outlet of the indoor heat exchanger; and - a controller configured to, when a measured value from the outdoor air temperature sensor is equal to or less than a predetermined value, perform a low-outside-air-temperature cooling operation mode, characterised in that in the low-outside-air-temperature cooling operation mode, the controller is configured to reduce a rotation speed of the outdoor fan, and to, when a difference between a measured value from the indoor heat exchanger outlet temperature sensor and a measured value from the indoor heat exchanger intermediate temperature sensor is equal to or greater than a first threshold, increase an opening degree of the pressure reducing device, the air-conditioning apparatus further comprising an indoor temperature sensor configured to measure an indoor temperature, wherein in the low-outside-air-temperature cooling operation mode, the controller is configured to, when the difference between the measured value from the indoor heat exchanger outlet temperature sensor and the measured value from the indoor heat exchanger intermediate temperature sensor is equal to or greater than the first threshold and a difference between the measured value from the indoor heat exchanger outlet temperature sensor and a measured value from the indoor temperature sensor is equal to or less than a third threshold, increase the opening degree of the pressure reducing device, wherein in the low-outside-air-temperature cooling operation mode, the controller is configured to, when the difference between the measured value from the indoor heat exchanger outlet temperature sensor and the measured value from the indoor heat exchanger intermediate temperature sensor is less than a second threshold, which is smaller than the first threshold, and the difference between the measured value from the indoor heat exchanger outlet temperature sensor and the measured value from the indoor temperature sensor is greater than the third threshold, decrease the opening degree of the pressure reducing device.