An air-conditioning apparatus includes a heat exchanger, a fan, and a controller. The heat exchanger causes heat exchange to be performed between a medium that transfers heat, and air. The fan sends air to the heat exchanger. The controller determines whether clogging due to foreign matter has occurred in the heat exchanger, based on a command voltage varying in accordance with the rotation speed of a fan motor that drives the fan.

To reduce the possibility that temperature of refrigerant discharged from a compressor of a refrigeration apparatus becomes excessively high by controlling torque of a motor built into the compressor, the compressor includes the motor having rotation thereof controlled by inverter control. An inverter controller controls torque of the motor using inverter control when operation frequency of the compressor is at least one value within a range of from 10 Hz to 40 Hz. When at least the operation frequency is within the range of from 10 Hz to 40 Hz, torque of the motor is controlled, and under a predetermined condition in which temperature of refrigerant discharged from the compressor easily becomes excessively high, a device controller controls devices provided in a refrigerant circuit such that refrigerant sucked into the compressor is placed in a wet vapor state.

An air conditioning apparatus 1 includes a compressor (321), an indoor heat exchanger (242) that is a use-side heat exchanger that exchanges heat with first air (F1), an outdoor heat exchanger (323) that is a heat-source-side heat exchanger that exchanges heat with second air, a refrigerant, a first duct (209), and a casing (230). The refrigerant contains at least 1,2-difluoroethylene, and circulates in the compressor (321), the indoor heat exchanger (242), and the outdoor heat exchanger (323) to repeat a refrigeration cycle. The first duct (209) supplies the first air (F1) to a plurality of rooms in an interior. The casing (230) includes a use-side space (SP2) that is connected to the first duct (209) and that accommodates the indoor heat exchanger (242). The casing (230) is configured to allow the first air (F1) after heat exchange with the refrigerant at the indoor heat exchanger (242) to be sent out to the first duct (209).

Disclosed is a heat pump system for an electric vehicle including an outdoor fan configured to blow air to an outdoor heat exchanger, a coolant temperature sensor installed at a coolant line and configured to detect a temperature of a coolant circulating in a power train module or a battery, an outdoor heat exchange sensor installed on one side of the outdoor heat exchanger and configured to detect an outdoor heat exchanger outlet pressure defined as a pressure of a refrigerant passing through the outdoor heat exchanger, and a compressor inlet sensor installed on an intake side of a compressor and configured to detect a compressor inlet temperature defined as a temperature of the refrigerant flowing into the compressor. Whether frost sticking occurs may be determined based on information detected by the coolant temperature sensor, the outdoor heat exchange sensor, and the compressor inlet sensor.

A heat pump system includes a refrigerant circuit, at least one compressor, an evaporator, and a controller programmed to defrost the evaporator in a defrost mode, wherein in the defrost mode the controller is programmed to monitor the evaporator to detect frost creation thereon, and reduce the speed of the at least one compressor and/or reduce the number of some, but not all operating compressors of the at least one compressor, if frost creation is detected on the evaporator. In some embodiments, the controller is programmed to defrost the evaporator in a second defrost mode. In the second defrost mode the controller is programmed to monitor the evaporator to detect frost creation thereon, turn off the at least one compressor when frost is detected on the evaporator, and operate a fan to force ambient air over the evaporator to defrost the evaporator.

A refrigeration cycle apparatus in which a compressor, a heat-source-side heat exchanger, a decompressor, and a use-side heat exchanger are connected by pipes to allow refrigerant to be circuited as a refrigeration cycle. The refrigeration cycle apparatus includes a controller which controls an operation of each of devices. The controller sets an operation mode to a specific operation mode for determining where abnormality occurs based on states of the compressor, the heat-source-side heat exchanger, the decompressor and the use-side heat exchanger in the case where an operating state of one of a plurality of element devices to be controlled by the controller is changed from a first state to a second state, the element devices being included in the compressor, the heat-source-side heat exchanger, the decompressor and the use-side heat exchanger.

A refrigeration cycle apparatus that is able to reduce the amount of refrigerant used while reducing a pressure loss in the case where a refrigerant containing at least 1,2-difluoroethylene is used is provided. In an air conditioner (1) including a refrigerant circuit (10), including a compressor (21), an outdoor heat exchanger (23), an outdoor expansion valve (24), and an indoor heat exchanger (31), and a refrigerant containing at least 1,2-difluoroethylene and sealed in the refrigerant circuit (10), the outdoor heat exchanger (23) has a heat transfer tube (23b) of which a pipe diameter is greater than or equal to 6.35 mm and less than 10.0 mm.

A refrigeration cycle apparatus that can improve operation efficiency when a refrigerant that contains at least 1,2-difluoroethylene is used is provided. An air conditioning apparatus 1 includes a compressor (21), an outdoor heat exchanger (23), an outdoor expansion valve (24), an indoor heat exchanger (31), and a suction injection pipe (40), and uses a refrigerant that contains at least 1,2-difluoroethylene. The suction injection pipe (40) allows a part of a refrigerant that flows toward the indoor heat exchanger (31) from the outdoor heat exchanger (23) to merge with a low-pressure refrigerant that is sucked into the compressor (21).

An air conditioning unit capable of performing a refrigeration cycle using a small-GWP refrigerant is provided. A refrigeration cycle apparatus (1, 1a to 1m) includes a refrigerant circuit (10) including a compressor (21), a condenser (23, 31, 36), a decompressing section (24, 44, 45, 33, 38), and an evaporator (31, 36, 23), and a refrigerant containing at least 1,2-difluoroethylene enclosed in the refrigerant circuit (10).

A refrigeration cycle apparatus includes a refrigerant circuit, a high-side pressure sensor, an outside air temperature sensor, an outdoor fan, a fan driving unit, and a controller. The controller includes a pressure prediction unit that predicts, based on a high-side pressure detected by the high-side pressure sensor, a predicted value of high-side pressure at the elapse of a set time, a fan rotation speed control unit that, during cooling operation in which an indoor heat exchanger acts as an evaporator, adjusts the rotation speed of the fan driving unit based on the outside air temperature detected by the outside air temperature sensor and the operating capacity of an indoor unit, and an intermittent fan control unit that, if the fan driving unit is running at a set lower limit rotation speed, and if the high-side pressure is below a target value, controls the fan driving unit to perform intermittent operation, the intermittent operation being performed by setting an ON time and an OFF time such that the predicted value predicted by the pressure prediction unit approaches the target value.