An illustrative example method of controlling a heat pump system includes operating in a defrost mode to provide heat to an outdoor heat exchanger for defrosting at least a portion of the outdoor heat exchanger, controlling a fan to be inoperative during the defrost mode, operating in a heating mode to provide heat within a temperature-conditioned space subsequent to operating in the defrost mode, controlling the fan to remain inoperative for an initial period at a beginning of operating in the heating mode, and controlling the fan to operate during the heating mode after the initial period to cause airflow across at least the portion of the outdoor heat exchanger.

An air-conditioning apparatus includes a heat source unit, a plurality of indoor units, and a relay unit. The heat source unit includes a heat-source-side flow control valve connected to a heat-source-side heat exchanger, a bypass pipe connected in parallel to the heat-source-side heat exchanger, a bypass flow control valve provided in the bypass pipe, and a gas-liquid separating unit configured to, when refrigerant flows out to the high-pressure pipe, mix refrigerant in a liquid state flowing through the heat-source-side heat exchanger and refrigerant in a gas state flowing through the bypass pipe and cause mixed refrigerant to flow out to the high-pressure pipe, and configured to, when refrigerant flows in from the low-pressure pipe, separate the refrigerant flowing in from the low-pressure pipe into refrigerant in a liquid state flowing into the heat-source-side heat exchanger and refrigerant in a gas state flowing into the bypass pipe.

An air-conditioning apparatus that includes a compressor, a flow switching device, an outdoor heat exchange unit, an expansion section and an indoor heat exchanger, which are connected by pipes, in which the outdoor heat exchange unit includes a first outdoor heat exchanger, a first flow rate control device, a second outdoor heat exchanger, a second flow rate control device, a bypass pipe, the second outdoor heat exchanger, the second flow rate control device, a third flow rate control device, and a flow control device.

An internal temperature adjusting device includes a heat pump, an internal heat exchanger, and an external heat exchanger. The internal heat exchanger is configured to function as one of an evaporator or a condenser of the heat pump, and exchange heat between a heat medium and air inside the container. The external heat exchanger is configured to function as the other one of the evaporator or the condenser, and exchange heat between the heat medium and air outside the container. The external heat exchanger includes a plurality of heat exchanging members separated from each other. According to the internal temperature adjusting device, drainage of the external heat exchanger as a whole can be secured.

An air conditioner of the disclosure includes a compressor; an indoor heat exchanger temperature sensor configured to sense an indoor heat exchanger temperature; an indoor humidity sensor configured to sense indoor humidity; and a controller configured to calculate a dew point temperature using the humidity value detected by the indoor humidity sensor and an indoor set temperature, and control a frequency of the compressor based on the calculated dew point temperature and the indoor heat exchanger temperature.

A vector control system is used to control a vapor compression circuit that includes a compressor motor. The vector control system is used to monitor the vapor compression circuit and adjust the speed of one or more motors within the vapor compression circuit to increase efficiency of the system by taking into account the torque forces placed on the compressor motor.

A heat exchanger includes: a plurality of flat pipes each having flat surfaces directed upward and downward, wherein the flat pipes are arranged in an up-down direction and extend in a fin stacking direction intersecting an air flow direction; and a plurality of heat transfer fins stacked in the fin stacking direction and each including: a plurality of cutouts into which the flat pipes are inserted, respectively, wherein the cutouts extend from a leeward side toward a windward side in the air flow direction; a plurality of fin main parts each formed between the cutouts adjacent to each other in the up-down direction; a fin windward part continuously extending from the fin main parts in the air flow direction toward the windward side of the cutouts; and a fin collar part extending from a peripheral portion of each of the cutouts toward one side in the fin stacking direction.

A system and method are described that help to alleviate pressure and strain spikes in and around dead tubes or frontiers between stages in a multi-stage condenser coil. Instead of cycling a fan off and on, fans associated with the condenser are kept running at a low speed instead of being turned off. Preventing the fans from turning off completely helps to even out the pressure and strain spikes. The present teachings can be especially beneficial in aluminum-based coils. The present teachings include both a unit controller that carries out the teachings, and a system based on temperature and/or pressure switches connected to a fan controller.

An air conditioning system includes a bypass passage and a cooling-heating switching mechanism. The bypass passage is configured to be at least a part of a flow passage connecting a third port to a refrigerant inlet of a compressor. A linear expansion valve opens and closes the bypass passage. The cooling-heating switching mechanism includes check valves and four-way valves. The four-way valve causes a refrigerant outlet of the check valve to communicate with one of the refrigerant inlet and a refrigerant outlet of the compressor. The four-way valve causes a refrigerant inlet of the check valve to communicate with one of the refrigerant inlet and the refrigerant outlet of the compressor and causes a port to communicate with the other of the refrigerant inlet and the refrigerant outlet.

A heat source side unit connected to load side units by pipes and constituting a refrigerant circuit, includes a compressor that compresses refrigerant and discharges the refrigerant, a heat source side heat exchanger that serves as an evaporator or a radiator, a gas-liquid separator that separates inflow refrigerant into liquid refrigerant and gas refrigerant, a liquid refrigerant outlet from which the liquid refrigerant flows out being connected to a connecting pipe at a refrigerant inflow side in a case where the heat source side heat exchanger serves as the evaporator, a sixth connecting pipe that connects a gas refrigerant outlet of the gas-liquid separator from which the gas refrigerant flows out to a pipe at a refrigerant outflow side in a case where the heat source side heat exchanger serves as the evaporator, and an expansion device that controls passage of refrigerant in the sixth connecting pipe.