An HVAC system includes a reversing valve configured to receive refrigerant and direct the received refrigerant based on an operating mode of the HVAC system. A sensor measures a heat-exchanger temperature associated with an outdoor heat exchanger. A controller monitors an outdoor temperature and the heat-exchanger temperature and compares these temperatures. The controller determines whether the HVAC system is intended to operate in a cooling or heating mode. If the heat-exchanger temperature is less than the outdoor temperature and the HVAC system is intended to operate in the cooling mode, the controller determines that a first reversing-valve fault is detected. The first reversing-valve fault is associated with the reversing valve being in the heating configuration when the HVAC system is intended to operate in the cooling mode.

An information processing apparatus obtains a heat load equation for calculating a heat load corresponding to a time at which a predetermined time period has elapsed from a current point in time using learning data concerning a heat load influencing factor of an air-conditioning apparatus, estimates, in a case where a compressor continues performing a low load operation, in which operation is performed at a standard operating frequency or less, for a predetermined time period or more, whether the heat load will become higher than the current point in time after the predetermined time period has elapsed using the heat load equation obtained, outputs, when estimating that the heat load will not become higher, an oil return command signal commanding that an operating frequency be increased to the compressor, and does not output, when estimating that the heat load will become higher, the oil return command signal to the compressor.

An HVAC system includes a reversing valve configured to receive refrigerant and direct the received refrigerant based on an operating mode of the HVAC system. The HVAC system includes first and second sensors. A sensor measures a heat-exchanger temperature associated with the outdoor heat exchanger. A controller monitors an outdoor temperature and the heat-exchanger temperature and compares these temperatures. The controller determines whether the HVAC system is intended to operate in a cooling or heating mode. If the heat-exchanger temperature is less than the outdoor temperature and the HVAC system is intended to operate in the cooling mode, the controller determines that a first reversing-valve fault is detected. The first reversing-valve fault is associated with the reversing valve being in the heating configuration when the HVAC system is intended to operate in the cooling mode.

A refrigerant control system includes: a reversing valve including: a first inlet configured to receive refrigerant output from a condenser; a first outlet configured to output refrigerant to an inlet of an evaporator located inside of a building; a second inlet configured to receive refrigerant output from the evaporator; and a second outlet configured to output refrigerant to an inlet of a compressor that pumps refrigerant to the condenser; a reversing module configured to: selectively actuate the reversing valve to a first position such that: refrigerant flows directly from the second inlet to the second outlet; and refrigerant flows directly from the first inlet to the first outlet; and selectively actuate the reversing valve to a second position such that: refrigerant flows directly from the second inlet to the first outlet; and refrigerant flows directly from the first inlet to the second outlet.

A refrigeration cycle apparatus includes a refrigeration cycle circuit, a bypass flow path, a first valve provided in the refrigeration cycle circuit, a second valve provided at the bypass flow path, a first temperature sensor configured to detect a temperature of an indoor space, a second temperature sensor configured to detect a temperature of refrigerant on a liquid side of an indoor heat exchanger, and a notification part. The refrigeration cycle apparatus is able to operate in an operation state where the compressor operates, the indoor heat exchanger functions as an evaporator, and the first valve is open while the second valve is closed. In the operation state, the notification part issues notification of an abnormality of an electronic expansion valve or the first valve when a temperature detected by the second temperature sensor is higher than an evaporation temperature of refrigerant in the refrigeration cycle circuit.

Heat pump systems with a gas bypass tank and that operate in both heating and cooling modes are disclosed. The systems include a first splitting valve that can route liquid refrigerant to either the indoor coil or the outdoor coil, depending on whether the heat pump system is in heating or cooling mode. An expansion valve in the system can lower the pressure of liquid refrigerant leaving a condenser, thereby creating a two-phase fluid comprising liquid refrigerant and vaporized refrigerant. The gas bypass tank can separate liquid refrigerant from vaporized refrigerant. The liquid refrigerant can be supplied to the evaporator of the system, while the vaporized refrigerant can be bypassed to a compressor. The first splitting valve can include a first plurality of switching paths that route the separated liquid refrigerant to either the outdoor coil or the indoor coil.

An HVAC system includes a reversing valve configured to receive compressed refrigerant and direct the refrigerant based on an operating mode. One or more suction-side sensors measure suction-side properties associated with refrigerant, including a suction-side temperature and a suction-side pressure. One or more liquid-side sensors measure liquid-side properties associated with the refrigerant. A controller monitors the suction-side pressure and liquid-side pressure and determines a ratio of the liquid-side pressure to the suction-side pressure. The controller further determines whether the suction-side temperature has an increasing trend. If the suction-side temperature has the increasing trend, the reversing valve is determined to be in an equalizing configuration. The equalizing configuration corresponds to a configuration in which the refrigerant provided from the outlet of the compressor is directed to the inlet of the compressor without first being directed to other components of the HVAC system.

An air conditioner includes two cut-off valves connected to respective refrigerant flow paths. At least one of the two cut-off valves is configured as a flow path switching valve configured to switch a flow path so as to block the refrigerant flow paths when a refrigerant leaks in a utilization circuit.

There is provided an air conditioner capable of displaying sufficient cooling ability in each indoor unit by allowing a sufficient amount of refrigerant to flow into indoor units where cooling ability cannot be displayed. By executing refrigerant amount balance control, since degrees of opening of indoor expansion valves are narrowed in indoor units whose refrigerant superheating degrees are smaller than an average refrigerant superheating degree, amounts of refrigerant flowing into the indoor expansion valves are decreased. In the indoor unit where the refrigerant superheating degree is higher than the average refrigerant superheating degree, since refrigerant pressure on a downstream side of the indoor expansion valve is also decreased due to the degrees of opening of the indoor expansion valves being narrowed, the difference in pressure between the upstream side and the downstream side of the indoor expansion valve increases and an amount of refrigerant flowing into the indoor unit is increased.

A heat pump system includes a compression device 12, a heat rejecting heat exchanger 14, an expansion device 18 and a heat absorbing heat exchanger 16; wherein the expansion device 18 provides a controllable degree of expansion. The heat pump system is operated in accordance with a method including determining a temperature indicative of frosting conditions on an exterior surface of the heat absorbing heat exchanger 16; operating the heat pump system in a first mode if the temperature indicative of frosting conditions is above a threshold value, and operating the heat pump system in a second mode if the temperature indicative of frosting conditions is within a range of temperatures that is below the threshold value.