An apparatus includes a microchannel heat exchanger, a load, a compressor, and a controller. The microchannel heat exchanger removes heat from a refrigerant. The load uses the refrigerant to remove heat from a space proximate the load. The compressor compresses the refrigerant from the load. The controller determines a discharge temperature of the refrigerant at the compressor and predicts a saturation temperature of the refrigerant between the compressor and the microchannel heat exchanger. The controller also determines a discharge superheat by subtracting the saturation temperature from the discharge temperature and triggers an alarm if the discharge superheat is below a threshold temperature.

A freezing device including a compressor that compresses sucked refrigerant using a compression mechanism and discharges compressed refrigerant includes a compressor, an inverter, and a controller. The compressor includes a motor, a low pressure unit, a compression space, a high pressure unit, a communication flow path, and a flow control valve. The inverter drives or stops the motor. The controller controls the inverter and the flow control valve. The controller performs, in stop control in which an operation of the compressor is stopped, braking control in which driving of the compression mechanism is prevented or suppressed, and pressure equalization control in which pressure in the high pressure unit is equalized with pressure in the low pressure unit.

The air conditioner includes: an outdoor unit that includes a compressor, an outdoor heat exchanger, and an outdoor expansion valve; an indoor unit that includes an indoor heat exchanger and an indoor expansion valve; a liquid pipe that connects the outdoor unit to the indoor unit; and a gas pipe that connects the outdoor unit to the indoor unit. One end of the outdoor heat exchanger is coupled to the liquid pipe through the outdoor expansion valve. One end of the indoor heat exchanger is coupled to the liquid pipe through the indoor expansion valve. When a predetermined period of time elapses after the compressor is shut down, the outdoor expansion valve and the indoor expansion valve both close.

Provided is an air-conditioning apparatus configured so that a decrease in a refrigeration capacity can be suppressed without increasing the amount of refrigerant with which a refrigerant circuit is filled and that refrigerant can be suitably stored during a pump down operation. The air-conditioning apparatus includes a first on-off valve provided at a pipe between an expansion valve and a use side heat exchanger, a bypass branching from a pipe between the expansion valve and the first on-off valve and connected to a pipe at a suction-side of a compressor, and a refrigerant storage unit configured to store the refrigerant having passed through the bypass. In a pump down operation in which the compressor operates with the first on-off valve being in a closed state, the refrigerant having flowed out from the heat source side heat exchanger flows into the bypass, and then, is stored in the refrigerant storage unit.