Abstract: According to one embodiment, the air conditioner comprises an outdoor unit, an indoor unit, a refrigerant cutoff unit, an airtight state detection unit, a notification unit, and a control unit. The control unit determines a refrigerant cutoff condition for whether or not to urge a flow of the refrigerant flowing into and from the indoor unit to be cut off and, if the refrigerant cutoff condition is satisfied, urges the refrigerant cutoff unit to cut off the flow, and urges the notification unit to notify a detection result of an airtight state of a pipe detected by the airtight state detection unit, in the indoor unit in which the flow of the refrigerant is cut off.

Abstract: According to one embodiment, a refrigeration cycle apparatus includes a main flow channel of a refrigerant, a compressor, a condenser, an evaporator, a branch channel, an expansion valve, a supercooling heat exchanger, an injection flow channel, and a control unit. The control unit determines, based on whether the determination condition is satisfied or not, a determination condition for adjusting an opening degree of the expansion valve and adjusts the opening degree of the expansion valve according to a first target value for a discharge temperature of the refrigerant from the compressor, or a second target value for a superheat degree of the refrigerant flowing through the injection flow channel.

Abstract: To provide a water heat exchanger, a manufacturing method of the water heat exchanger, and a refrigeration cycle apparatus capable of preventing corrosion of a brazing material and deterioration of a refrigerant. The water heat exchanger according to the present embodiment includes a plurality of stacked heat-exchange plates, a joint (9) provided on at least one cover plate (14) of a pair of cover plates sandwiching the plurality of heat exchange plates, a first refrigerant pipe (10) brazed to the joint (9) by a brazing material (11), and a protector (12) provided to prevent contact between the brazing material (11) and the refrigerant circulating to the plurality of heat exchange plates through the first refrigerant pipe (10) and the joint (9).