Air conditioning apparatus with compressor discharge pressure sensing

An air conditioning apparatus comprising:

• one or a plurality of indoor units each having an indoor heat exchanger, and an indoor expansion valve in which a degree of opening is variable;
• an outdoor unit having an outdoor heat exchanger, a four-way valve, a compressor, a discharge pressure sensor configured to detect a pressure of a refrigerant discharged from the compressor, and a temperature sensor configured to detect a temperature of outside air;
• and
• a controller configured to control each indoor expansion valve, the four-way valve, and the compressor, the controller configured to store a total value of a period during which a temperature detected by the temperature sensor is less than a predetermined temperature threshold value after a start of a heating operation, the controller configured to determine whether or not the total value of the period is equal to or greater than a predetermined reference time, the controller configured to determine whether or not a discharge pressure detected by the discharge pressure sensor is equal to or higher than a predetermined pressure threshold value,
• wherein the one or plurality of indoor units are connected to the outdoor unit,
• wherein the controller is configured to start a defrosting operation when the total value of the period becomes equal to or greater than the reference time,
• wherein the controller is configured such that when the controller determines that the discharge pressure is equal to or higher than the pressure threshold value while the heating operation is performed, the controller sets a maximum time for continuing the defrosting operation to a first maximum time, and
• wherein the controller is configured such that when the controller determines that the discharge pressure is less than the pressure threshold value while the heating operation is performed, the controller sets the maximum time for continuing the defrosting operation to a second maximum time shorter than the first maximum time.