A target condensing temperature and a target evaporating temperature are changed in accordance with a load of each load side unit obtained by using load detection means, and an operating frequency of a compressor and a rotation speed of a fan are controlled such that a condensing temperature obtained by using temperature detection means coincides with the target condensing temperature and an evaporating temperature obtained by using the temperature detection means coincides with the target evaporating temperature.

An air conditioning apparatus includes a refrigerant circuit in which a plurality of indoor units respectively including an indoor heat exchanger and an indoor expansion valve are connected to an outdoor unit including an outdoor expansion valve via a liquid-refrigerant connection pipe. The air conditioning apparatus individually controls each of the indoor units to operate or stop. The air conditioning apparatus includes a controller. When at least one of the indoor heat exchangers functions as a radiator, the controller controls an opening degree of the indoor expansion valve and an opening degree of the outdoor expansion valve. The apparatusdetermines whether a refrigerant amount in the refrigerant circuit is appropriate on the basis of an amount of change corresponding to a change in state of a refrigerant between the indoor expansion valve and the outdoor expansion valve.

A failure diagnosis system diagnoses the state of an air-conditioning apparatus having a refrigerant circuit in which refrigerant circulates. The failure diagnosis system has an abnormality diagnosis unit that performs normal-operation abnormality diagnosis for determining whether or not there is an abnormality in the air-conditioning apparatus by using state data and control data during normal operation of the air-conditioning apparatus. If the abnormality diagnosis unit determines that there is an abnormality, it changes a control value for an actuator of the air-conditioning apparatus and acquires state data and control data. Then, the abnormality diagnosis unit performs abnormality-cause identification diagnosis for identifying the cause of the abnormality in the air-conditioning apparatus by using the state data and the control data acquired before the change of the control value and the state data and the control data acquired after the change of the control value.

A liquid level detector includes: a vertically-mounted accumulator that stores refrigerant; a heater that heats the accumulator; a temperature detector that detects a surface temperature of the accumulator; a pressure detector that detects a pressure of the refrigerant in the accumulator; and a controller. The controller detects a position of a liquid surface of the refrigerant in the accumulator based on a surface temperature of the accumulator detected by the temperature detector when the accumulator is heated by the heater, and a pressure of the refrigerant in the accumulator detected by the pressure detector.

A refrigeration cycle apparatus includes a refrigeration cycle through which refrigerant is circulated, an indoor unit that accommodates at least a load-side heat exchanger of the refrigeration cycle and is placed indoors, and a controller that controls the indoor unit. The indoor unit includes an indoor air-blowing fan, an air inlet through which indoor air is sucked in, and an air outlet through which the air sucked in from the air inlet is blown indoors. The controller activates the indoor air-blowing fan when leakage of refrigerant is detected. An air passage that allows air to pass through the air outlet is established in the air outlet at least when leakage of refrigerant is detected.

A refrigeration cycle apparatus includes a refrigerant circuit including a compressor, a condenser (outdoor heat exchanger), an expansion valve, and an evaporator (indoor heat exchanger), a fan configured to blow air to the condenser, a fan configured to blow air to the evaporator, and a controller configured to control at least one of a frequency of the compressor, an opening degree of the expansion valve, a rotation speed of the fan, and a rotation speed of the fan, such that the refrigerant sucked into the compressor has a quality of 1.0 or greater. The refrigerant circuit is configured for use with a refrigerant mixture inclusive of 30 wt % to 50% wt ethylene-based hydrofluorocarbon refrigerant.

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 refrigeration cycle system includes a refrigeration cycle apparatus, an operation signal transmitter, a detection unit, a notification unit, and a processing unit. The refrigeration cycle apparatus includes a refrigerant circuit. The operation signal transmitter transmits an operation signal for the refrigeration cycle apparatus. The detection unit detects leakage of a refrigerant. The notification unit notifies of leakage of the refrigerant by emitting at least one of sound and light in a case in which the detection unit has detected leakage of the refrigerant. The processing unit causes the notification unit to execute test behavior of emitting at least one of sound and light in a case in which the operation signal transmitter transmits the operation signal to the refrigeration cycle apparatus.

An air conditioning system includes an air conditioning device, a detector, and an alarm. The air conditioning device has a control unit and conditions air in an indoor space. The detector detects the concentration of refrigerant in the indoor space. The alarm notifies of refrigerant leakage in the indoor space. The detector or the alarm transmits information indicating whether or not the detector and the alarm are connected to each other in a wired or wireless manner, to the control unit. The control unit inhibits operation of the air conditioning device when the information indicates that the detector and the alarm are not connected to each other in the wired or wireless manner.

A vehicle air conditioning apparatus can ensure that the temperature of the air supplied to the vehicle interior is a preset temperature by securing the quantity of heat release for the radiator during a cooling and dehumidifying operation. The valve opening of the condensing pressure regulating part of the first control valve is smaller when the calculated opening SW of the air mix damper is equal to or more than the predetermined value than when the opening SW is smaller than the predetermined value. Accordingly, when the quantity of heat release is not sufficient in the radiator, it is possible to increase the condensing pressure of the refrigerant in the radiator to raise the temperature of the refrigerant in the radiator. Consequently, it is possible to secure the amount of heating, and therefore to ensure that the temperature of the air supplies to the vehicle interior is a preset temperature.