An air-conditioning apparatus includes a four-way valve, a first three-way valve and a second three-way valve each having a closed port, a compressor, an indoor heat exchanger, an expansion valve, a first outdoor heat exchanger, a second outdoor heat exchanger, a bypass expansion valve, a check valve, a discharge temperature sensor, an indoor pipe temperature sensor, an indoor temperature sensor, a current sensor, and a controller configured to detect switching failure at the four-way valve, the first three-way valve, and the second three-way valve. The controller is configured to detect switching failure at the four-way valve, the first three-way valve, or the second three-way valve by using the temperatures measured by the discharge temperature sensor, the indoor pipe temperature sensor, and the indoor temperature sensor and the current in consideration of an operation status.

A heat pump system and a control method therefor. The heat pump system includes a compressor; an indoor heal exchanger; an outdoor heat exchanger, including a first heat exchange portion and a second heat exchange portion, wherein a flow path switching device is provided between the first heat exchange portion and the second heat exchange portion to disconnect or communicate the first heat exchange portion and the second heat exchange portion; a first four-way valve; and a second four-way valve, configured to enable a high-temperature refrigerant to be input into the first heat exchange portion in a heating mode, so as to enable the heat pump system to operate in a heating and deicing mode.

A heat exchanger includes a plurality of heat exchange units each including a plurality of flat tubes, a plurality of fins, an upper header, and a lower header. In the plurality of heat exchange units, the upper headers are connected such that the upper headers communicate with each other, and the lower headers are connected such that the lower headers communicate with each other through an opening-closing valve. The heat exchanger has a configuration in which when the heat exchanger serves as a condenser, the opening-closing valve is controlled such that refrigerant in at least one of the plurality of heat exchange units flows in an upward direction, and refrigerant in the other one or the other ones of the plurality of heat exchange units flows in a downward direction.

Provided is a refrigeration cycle apparatus capable of achieving an improvement in heat exchange performance during a heating operation and during a cooling operation, while suppressing increases in manufacturing cost and volume required for packaging. The outdoor heat exchanger and the outdoor heat exchanger are connected in parallel to the indoor heat exchanger via the branch portion. The flow path switching device includes a first port, a second port, and a third port. The first port is connected with a third refrigerant flow path. The second port is connected with the outdoor heat exchanger. The third port is connected with a fourth refrigerant flow path. The second port is configured to switch between a state in which the second port is connected to the first port and a state in which the second port is connected to the third port.

An air conditioner may include a plurality of indoor units and a plurality of outdoor units connected to the plurality of indoor units. Each of the plurality of outdoor units may include a plurality of outdoor heat exchangers. Each of the outdoor heat exchangers may include a plurality of heat exchanger parts. When a defrosting operation condition is satisfied during a heating operation, indicating that a defrosting operation should be performed the plurality of heat exchanger parts of the plurality of outdoor heat exchangers may successively perform the defrosting operation.

An apparatus includes a compressor, a first heat exchanger, a reheater, a first valve, a second heat exchanger, and a blower. The compressor compresses a refrigerant. The blower moves air proximate the second heat exchanger to the reheater. During a first mode of operation: the first heat exchanger removes heat from a first portion of the refrigerant from the compressor, the first valve opens such that a second portion of the refrigerant from the compressor flows to the reheater, the second heat exchanger uses the first portion of the refrigerant from the first heat exchanger and the second portion of the refrigerant from the reheater to cool air proximate the second heat exchanger, and the reheater uses the second portion of the refrigerant from the compressor to heat the air moved by the blower.

A refrigeration cycle apparatus includes: a first four-way valve having first to fourth ports; a second four-way valve and a third four-way valve each having fifth to eighth ports; a compressor; a discharge pipe connecting a discharge port of the compressor and the first port; a suction pipe connecting a suction port of the compressor and the second port; a first high pressure pipe connecting the discharge pipe and the fifth ports; a second high pressure pipe connecting the third port and the first high pressure pipe; a first valve provided at the first high pressure pipe; a second valve provided at the second high pressure pipe; a low pressure pipe connecting the suction pipe and the sixth ports; a first outdoor heat exchanger connected with the seventh port of the second four-way valve; a second outdoor heat exchanger connected with the seventh port of the third four-way valve; and an indoor heat exchanger connected with the fourth port.

An air-conditioning apparatus includes a first flow switching unit configured to be switched between a first state in which refrigerant communication between a compressor and a second load-side heat exchanger is blocked and a second state in which the compressor is in refrigerant communication with a first load-side heat exchanger and the second load-side heat exchanger. The air-conditioning apparatus further includes a second flow switching unit configured to be switched between a third state in which refrigerant communication between the second load-side heat exchanger and a heat-source-side heat exchanger is blocked and a fourth state in which the first load-side heat exchanger is in refrigerant communication with the second load-side heat exchanger and the heat-source-side heat exchanger. The first heat exchanger is located upstream of the second load-side heat exchanger. The second flow switching unit is located downstream of the second load-side heat exchanger.

An air-conditioning apparatus includes a refrigerant circuit, an air-conditioning load state detection unit, an operation-state detection unit, and a controller. The refrigerant circuit includes a main circuit and a bypass circuit. The air-conditioning apparatus has a simultaneous heating and defrosting operation mode. In the simultaneous heating and defrosting operation mode, the controller controls a compressor, a pressure reducing device, and a defrosting refrigerant pressure-reducing device such that control amounts of the compressor, the pressure reducing device, and the defrosting refrigerant pressure-reducing device reach respective normal-time control target values that are set based on an air-conditioning load state and an operation state.

A refrigeration cycle apparatus includes: a compressor; an indoor heat exchanger; an outdoor heat exchanger including first and second outdoor heat exchangers; a bypass flow passage causing a discharge side of the compressor to communicate with the first or second outdoor heat exchanger; a flow control valve at the bypass flow passage; and a controller performing a heating operation in which the first and second outdoor heat exchangers operate as an evaporator and the indoor heat exchanger operates as a condenser and a simultaneous heating and defrosting operation in which part of refrigerant the compressor discharges is supplied to one of the first and second outdoor heat exchangers through the bypass flow passage, the other of the outdoor heat exchangers operates as an evaporator, the indoor heat exchanger operates as a condenser, and an upper limit frequency of the compressor changes to a value higher than in the heating operation.