An air conditioning system includes a control unit, a circulation system, an AC-to-DC conversion unit, and a fan module. The control unit detects an area temperature, controls the compressor unit being in operation or not in operation according to the area temperature and a setting temperature set by the control unit, and control a rotation speed of the condensing fan according to a temperature difference between the area temperature and the setting temperature. When the area temperature is greater than the setting temperature, the control unit controls the compressor unit being in operation and control the condensing fan being in full-speed operation.

A method of detecting electrical failure in a refrigeration system is provided. The method includes determining whether a present superheat of the refrigeration system is between a maximum superheat and a minimum superheat for the refrigeration system, the maximum superheat and the minimum superheat defining a normal operating range. The method also includes detecting an electrical property of an expansion valve assembly of the refrigeration system responsive to the superheat being outside the normal operating range. The method further includes determining whether the expansion valve assembly as experienced an electrical failure based on at least the electrical property. A signal indicating that the expansion valve has experienced an electrical failure is generated based on a determination that the expansion valve assembly has experienced the electrical failure.

The disclosed technology includes systems and methods of reducing frost accumulation on a heat pump evaporator coil. The disclosed technology can include a heat pump assembly having an evaporator coil, a fan configured to direct air across the evaporator coil, a temperature sensor, and a controller configured to energize the fan to direct air across the evaporator coil when the temperature of the evaporator coil is below a threshold temperature.

A freezer case includes a refrigeration system and a controller. The controller is configured to store a plurality of setpoint instruction sets associated with a plurality of possible operating modes, select a current operating mode from the plurality of possible operating modes, assign a value for the superheat setpoint by executing the setpoint instruction set associated with the current operating mode, control the refrigeration system in accordance with the superheat setpoint.

A household refrigeration appliance has a thermally-insulated body with an interior container that delimits a coolable interior space, a refrigeration circuit for cooling the coolable interior space and at least one fan. During the proper operation of the household refrigeration appliance, the fan is operated in a closed loop speed-controlled manner according to an at least indirectly specified desired rotational speed of the fan. During an inspection mode, the fan is operated without closed loop speed control, the actual rotational speed of the fan is ascertained and the actual rotational speed is evaluated in order to detect an abnormal operating state of the fan.

An air-conditioning apparatus includes a first indoor unit and an outdoor unit in a single refrigeration cycle and connected via a first refrigerant pipe. The first indoor unit is provided with a first refrigerant leakage sensor configured to detect leakage of refrigerant and a concentration of leaked refrigerant, and the outdoor unit includes a compressor, a first flow control valve configured to adjust a flow rate of the refrigerant flowing through the first refrigerant pipe, and a control unit configured to stop the compressor and fully close the first flow control valve when leakage of the refrigerant flowing through the first refrigerant pipe is detected by the first refrigerant leakage sensor, and configured to change an opening speed of the first flow control valve to a speed less than an opening speed of the first flow control valve adopted before the leakage of the refrigerant is detected.

In an embodiment, a method of preventing evaporator coil freeze in a heating, ventilation and air conditioning (HVAC) system is performed by a controller in the HVAC system. The method includes determining a reference saturated suction temperature (SST) via a sensor disposed in relation to an evaporator coil in the HVAC system. The method also includes determining whether the reference SST is below a minimum SST threshold. The method also includes, responsive to a determination that the reference SST is below the minimum SST threshold, increasing a discharge air temperature (DAT) setpoint.

An air conditioning system is provided. The system has a high-pressure pipe, a low-pressure pipe, an indoor heat exchanger, an outdoor heat exchanger, a leak-free thermal expansion valve and a variable capacity compressor. The variable capacity compressor has a shell, a first cylinder and a second cylinder. The shell has a suction port and an exhaust port. The first cylinder has a first suction hole connected to the suction port and a first exhaust hole connected to the exhaust port. The second cylinder has a second suction hole connected to the suction port, a second exhaust hole connected to the exhaust port, and a pressure relief hole connected to the high-pressure pipe and the low-pressure pipe in an on-off manner. Before the variable capacity compressor is started, the high-pressure pipe and the low-pressure pipe are connected and also disconnected after the first preset duration.

A control method for controlling a refrigerator includes a first step for driving a compressor for compressing a refrigerant and a fan for moving air, a second step for driving the compressor and stopping the fan, a third step for stopping the compressor and driving the fan, and a fourth step for stopping the compressor and the fan.

A CO.sub.2 based refrigeration system and a method of operating the CO.sub.2 based refrigeration system. The system includes a condenser configured to transfer heat from a CO.sub.2 refrigerant of the refrigeration system to an air stream. The system also includes an indirect evaporative cooler arranged to cool an ambient air stream without changing its moisture content and to supply the cooled ambient air to the condenser to facilitate the transfer of heat from the CO.sub.2 refrigerant.