A refrigeration cycle apparatus according to the present invention, a controller is configured to cause a first operation mode and a second operation mode to be executed as operation modes of an air-sending fan. The first operation mode is an operation mode in which an operation of the air-sending fan is started based on a first manipulation performed on an operation unit and the air-sending fan is stopped based on a second manipulation performed on the operation unit. The second operation mode is an operation mode in which the operation of the air-sending fan is started when refrigerant is detected by a refrigerant detection unit, the air-sending fan is not stopped based on the second manipulation, the air-sending fan is stopped based on a third manipulation different from the second manipulation, and the operation of the air-sending fan is restarted based on a fourth manipulation different from the first manipulation.

A refrigeration cycle apparatus includes a refrigeration cycle circuit which includes a plurality of load-side heat exchangers; a plurality of indoor units which accommodate the plurality of load-side heat exchangers, respectively; and a controller which controls the plurality of indoor units. Each of the plurality of indoor units includes an air-sending fan. At least one of the plurality of indoor units includes a refrigerant detection unit. The controller divides the plurality of indoor units into one or more groups. The controller is set such that when refrigerant is detected by the refrigerant detection unit included in any of the plurality of indoor units, the controller causes the air-sending fans included in all the indoor units which belong to a same group as the indoor unit which includes the refrigerant detection unit which detects the refrigerant to be operated.

A method for defrosting a heat pump includes operating a fan at a particular speed. The fan is positioned to circulate air across the exterior coil of the heat pump. The method also includes measuring a power of the fan while the fan is operating at the particular speed and initiating a defrost of the exterior coil of the heat pump when the power of the fan is less than a threshold power.

A sealed heat exchange system and air conditioner are provided herein. The sealed heat exchange system may include a compressor, a heat exchanger, a line filter, a variable electronic expansion device, a primary fluid path, and an alternate fluid path. The compressor may generally increase a pressure of a flowed refrigerant within the sealed heat exchange system. The heat exchanger may be in fluid communication with the compressor and the line filter may be in fluid communication with the heat exchanger. The primary fluid path may define a fluid inlet to receive the flowed refrigerant downstream of the heat exchanger and upstream of the expansion device. The alternate fluid path may define a fluid inlet to receive the flowed refrigerant downstream of the variable electronic expansion device and upstream of the heat exchanger.

Provided is a refrigeration cycle apparatus including a refrigerant circuit configured to circulate refrigerant, a heat exchanger unit accommodating a heat exchanger of the refrigerant circuit, and a controller configured to control the heat exchanger unit, in which the heat exchanger unit includes an air-sending fan, and an electric refrigerant detection unit, the controller is configured to operate the air-sending fan when the controller detects leakage of the refrigerant on the basis of a detection signal from the electric refrigerant detection unit, and the controller is configured to stop electric supply to the electric refrigerant detection unit when a rotation speed of the air-sending fan becomes equal to or larger than a first threshold value under a state in which the electric refrigerant detection unit is supplied with electricity.

An air-conditioning apparatus includes at least one indoor unit with intake and blow-out ports, a refrigerant gas sensor disposed in an air flow path inside the indoor unit; and a control device. The indoor unit has an indoor fan drawing indoor air in from the intake port and blowing conditioned air out from the blow-out port, an indoor temperature sensor detecting temperature of the indoor air, an indoor-side refrigerant circuit circulating a refrigerant having a greater specific gravity when gasified than air and producing conditioned air from the indoor air, and at least one refrigerant temperature sensor detecting refrigerant temperature in the refrigerant circuit. The control device drives the indoor fan in accordance with at least one of an operation mode and a detection value of the at least one refrigerant temperature sensor, and detects refrigerant leakage using the refrigerant gas sensor.

A refrigeration cycle device includes: a refrigeration cycle circuit including: a compressor and an indoor heat exchanger; an indoor air-sending device including a fan and a motor to supply air to the indoor heat exchanger; and a controller to control the frequency of the compressor and the rotation speed of the motor. The controller controls the rotation speed of the motor by controlling a frequency of an alternating current output from an inverter to the motor. The inverter is disposed at a position exposed to air heat-exchanged in the indoor heat exchanger. The controller controls the frequency of the compressor to a frequency at which a temperature of the inverter becomes lower than a first prescribed temperature in a state where the rotation speed of the motor is lower than a prescribed rotation speed.

A controller controls a first air-conditioning system and a second air-conditioning system having separate refrigerant circuits, but arranged for conditioning a common space. The controller includes a multi-variable regulator to determine control signals for controlling operations of first components of the first and the second refrigerant circuits to reduce jointly and concurrently an environmental error between setpoint and measured values of environment in the common space. The controller also includes at least two single-variable regulators to receive operational errors between setpoint and measured values of an operation of a second component of the first and the second refrigerant circuits. The controller separately determines control signals for controlling the operation of different refrigerant circuits that reduce the operational errors. The controller also includes a lookup table that stores values for other inputs of the systems that improve its performance, and which selects specific input values for both systems according to the outputs of the multi-variable and/or single variable regulators. The controller includes an electrical circuit for controlling the first and the second air-conditioning systems according to the determined control signals.

A method for controlling a heat pump is provided. A working mode of the heat pump is determined. Based on a determination that the working mode of the heat pump is a heating mode, an ambient temperature of the heat pump is determined. Based on a determination that the ambient temperature of the heat pump is higher than a first predetermined temperature, a first compressor of the heat pump is operated. Based on a determination that the ambient temperature of the heat pump is lower than the first predetermined temperature, both the first compressor and a second compressor of the heat pump are enabled to operate, in response to a two-stage thermostat. The first compressor and the second compressor are coupled in parallel. The method allows the heat pump to be suitable for a cold climate.

An air-conditioning device which melts a large amount of frost deposited thereon while maintaining the proper operation of a compressor by setting the defrosting operation time according to the low pressure of the compressor. This air-conditioning device has: a refrigerant circuit which has a compressor, a refrigerant flow path switching device, a heat-source-side heat exchanger, a throttle device, and a use-side heat exchanger being connected by refrigerant pipes, and configures a refrigeration cycle; a pressure sensor which detects the pressure on the intake side of the compressor; and a control device which, during defrosting operation, controls the refrigerant flow path switching device and supplies the compressed refrigerant from the compressor to the heat-source-side heat exchanger, compares the detection value of the compressor sensor and a first threshold value, and changes defrosting operation time on the basis of the comparison result.