Air Conditioning Device

An air conditioning device, comprising:

• a refrigerant circuit that is formed of a compressor, a first heat exchanger, an expansion valve, and a second heat exchanger connected to one another by a first pipe through which a refrigerant flows, the refrigerant circuit being capable of performing a defrosting operation in which the refrigerant discharged from the compressor is introduced into the second heat exchanger;
• a heat-transfer medium circuit that is formed of a pump, the first heat exchanger, and a third heat exchanger connected to one another by a second pipe through which a heat-transfer medium flows;
• and
• a control device that controls the compressor and the pump, wherein
• the control device performs the defrosting operation while keeping heating, with a heating capability of the third heat exchanger during the defrosting operation set to a capability that is determined based on an amount of heat storage of the heat-transfer medium within the heat-transfer medium circuit, and
• when the amount of heat storage of the heat-transfer medium is less than a threshold, the control device reduces the heating capability of the third heat exchanger when the air conditioning device transitions from a heating operation to the defrosting operation.