When a refrigerant leakage sensor detects a leakage of refrigerant from a refrigeration cycle apparatus having an indoor unit and an outdoor unit, a refrigerant recovery operation is started. In the refrigerant recovery operation, refrigerant is recovered in an accumulator and afterward a pump down operation is performed. In recovery of refrigerant in the accumulator, refrigerant in a liquid phase is accumulated in the accumulator as a result of circulation of refrigerant by operating a compressor in the state where a liquid shut-off valve and a gas shut-off valve are opened. After recovery of refrigerant in the accumulator is ended, the refrigerant in a liquid phase is accumulated in an outdoor heat exchanger by the pump down operation for operating the compressor in the state where the liquid shut-off valve is closed.

In a power converter, an inductance L of a reactor and a capacitance C of a capacitor satisfy a condition of the expression (1) below. In the power converter, a current-limiting circuit between an AC power source and the capacitor is unnecessary. Herein, αm ([A.Math.s]) is a value of a ratio of a maximum rated current squared time product to a maximum rated output current of diodes of a rectifier circuit, Pmax is a maximum power consumption of the motor, Vac is a voltage value of a three-phase AC voltage, and a value of a constant a is 4.3 $\begin{array}{cc}a.Math.C.Math.\sqrt{\frac{C}{L}}.Math.\frac{{\mathrm{Vac}}^3}{P_{\max }}\le {\alpha }_m.& \left(1\right)\end{array}$

A heat pump including a housing configured to be disposed outdoors; a compressor that compresses a refrigerant; a fluid refrigerant heat exchanger configured to perform heat exchange between the refrigerant and a fluid; an outdoor heat exchanger configured to perform heat exchange between the refrigerant and outdoor air; a pressure sensor configured to detect a pressure of the refrigerant flowing between the compressor and the fluid refrigerant heat exchanger; a first shut-off valve disposed in a pipe connected to a discharge of the compressor; a second shut-off valve disposed between the outdoor heat exchanger and the compressor; and a controller configured to: determine whether the refrigerant leaks, control the first shut-off valve to be closed, when the refrigerant leaks, and control the second shutoff valve to be closed, when the pressure sensed by the pressure sensor is less than a predetermined reference pressure.

A refrigeration cycle apparatus comprises a refrigerant circuit and a refrigerant storage circuit. In the refrigerant circuit, a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected together by a pipe. The pipe has a first pipe portion and a second pipe portion. The first pipe portion connects the outdoor heat exchanger to the expansion valve. The second pipe portion connects the indoor heat exchanger to the compressor. The refrigerant storage circuit has a storage container, an expander, and a valve device. The storage container stores refrigerant. The expander is located between the storage container and the second pipe. The valve device is located between the first pipe and the expander. The valve device is configured to open and close the refrigerant storage circuit.

A refrigeration cycle apparatus (1) is capable of performing a refrigeration cycle using a small-GWP refrigerant. The refrigeration cycle apparatus (1) includes a refrigerant circuit (10) and a refrigerant enclosed in the refrigerant circuit (10). The refrigerant circuit includes a compressor (21), a condenser (23), a decompressing section (24), and an evaporator (31). The refrigerant contains is a small-GWP refrigerant.

Upon detection of a leakage of refrigerant, a refrigerant recovery operation is performed for operating a compressor in a state where an outdoor expansion valve is closed. The refrigerant suctioned from an indoor unit passes through an outdoor heat exchanger so as to be liquefied and accumulated in an outdoor unit. When a low-pressure detection value by a pressure sensor decreases below a reference value, a termination condition for the refrigerant recovery operation is satisfied, and the compressor is stopped. Furthermore, when an abnormality in the refrigerant recovery operation is detected based on a behavior of the low-pressure detection value obtained until the termination condition is satisfied, the compressor is stopped to thereby end the refrigerant recovery operation. Also, guidance information for notification about an abnormality is output to a user.

An air conditioner and a control method thereof. The air conditioner includes an indoor unit including an indoor heat exchanger and an indoor fan, an outdoor unit connected to the indoor unit and including an outdoor heat exchanger, an outdoor fan, a compressor, an expansion valve, and a four-way valve, and at least one processor configured to perform a test operation by controlling the indoor unit and the outdoor unit. Based on an outdoor temperature being less than a predetermined reference temperature, the at least one processor is configured to determine whether the indoor unit and the outdoor unit operate normally, by continuously performing a heating operation and a defrosting operation during the test operation.

A refrigerant cycle apparatus, that circulates a flammable refrigerant in a refrigerant circuit, includes: a gas-side cutoff valve; a liquid-side cutoff valve, where the gas-side cutoff valve and the liquid-side cutoff valve are disposed on opposite sides of a first portion of the refrigerant circuit; a detection unit that detects refrigerant leakage from the first portion into a predetermined space; and a control unit that sets a cutoff state in the gas-side cutoff valve and the liquid-side cutoff valve when the detection unit detects the refrigerant leakage from the first portion into the predetermined space. The cutoff leakage rate at the gas-side cutoff valve is higher than the cutoff leakage rate at the liquid-side cutoff valve.

A refrigeration cycle apparatus includes an outdoor unit a plurality of indoor units a relay unit a refrigerant circuit and a controller The relay unit includes a plurality of high-pressure valves and a plurality of low-pressure valves The controller when an operation state of at least one of the indoor units is changed from a first state to a second state, judges, based on a degree of supercooling of an outlet of the outdoor heat exchanger or the indoor heat exchanger or based on a degree of superheating of a suction side of the compressor, whether an abnormality is present in the plurality of high-pressure valves or the plurality of low-pressure valves.

An air-conditioning apparatus includes a compressor, an indoor heat exchanger, a first outdoor heat exchanger and a second outdoor heat exchanger, a valve between the second outdoor heat exchanger and the indoor heat exchanger switching between an opened state and a closed state, a temperature sensor detecting a temperature of refrigerant that flows into the second outdoor heat exchanger and liquefies, and a condensing-temperature detection device, wherein during first cooling operation in which the first outdoor heat exchanger functions as a condenser, the indoor heat exchanger functions as an evaporator, and the valve is in the closed state, when a comparative temperature becomes equal to or higher than a prescribed temperature, the air-conditioning apparatus switches to second cooling operation in which the valve is brought into the opened state, the comparative temperature being a value obtained by subtracting a temperature detected by the temperature sensor from the condensing temperature.