A control method and device for an air conditioner outdoor unit, an outdoor unit and an air conditioner are provided. The outdoor unit has a compressor, a first sensor for detecting an air exhaust pressure of the compressor, and a second sensor for detecting an air return pressure of the compressor. According to the method, a target pressure value is determined; an air exhaust pressure value detected by the first sensor or an air return pressure value detected by the second sensor is periodically obtained as a first pressure value; and the frequency of the compressor is adjusted according to the first pressure value and the target pressure value.

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

Air conditioner units and methods of operating the same are provided. A method of operating an air conditioner unit includes determining a fan speed as a function of a compressor speed of a variable speed compressor of the air conditioner unit. The method also includes activating a variable speed fan of the air conditioner unit at the fan speed. An air conditioner unit may include a controller, and the controller may be configured for performing the method.

An EXV (electronic expansion valve) control system includes an EXV controller for controlling an EXV within the refrigerant loop of an HVAC system. The EXV controller implements a master control algorithm that includes a plurality of sub-control algorithms and an initial series of branching decision points to determine the current mode of operation and to execute select sub-control algorithms corresponding to the current mode of operation, while not executing the sub-control algorithms corresponding to the other modes of operation. The sub-control algorithms implement various combinations of PID (Proportional Integral Derivative) control and feed-forward control, the results of which can be mapped to specific control instructions for the EXV.

An oil return control method for a multi-split air conditioner and a system accomplishing the same includes: calculating an average exhaust pressure within an oil return period Pd_AVG; determining whether the average exhaust pressure Pd_AVG≥the set threshold Pd.sub.threshold; if Pd_AVG≥Pd.sub.threshold, maintaining the multi-split air conditioner working in heating mode to ensure an acceptable oil return performance without affecting the air conditioning effect of indoor unit in heating mode; if Pd_AVG<Pd.sub.threshold, switching the multi-split air conditioner to cooling mode, stopping a fan within those power-on indoor units and entering into a cooling oil return process and switching the multi-split air conditioner back to heating mode until the cooling oil return process ends.

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).

Provided is an air conditioning apparatus that sufficiently raises the temperature of hot air to be blown out when receiving a request for high-temperature air temporarily raising the temperature of the hot air. A first use side unit includes a first use side heat exchanger and a first use side fan. A second use side unit includes a second use side heat exchanger and a second use side fan. When the first use side unit receives a request for the high-temperature air and the second use side unit receives no request for the high-temperature air, the air conditioning apparatus shifts to a mode that performs control to reduce the airflow volume of the second use side fan or make the airflow volume of the second use side fan zero such as reducing the number of revolutions of the second use side fan in another room by 40 rpm.

Methods and related systems for controlling superheat in a climate control system are disclosed. In an embodiment, the method includes (a) determining a superheat of a refrigerant downstream of a coil of a heat exchanger of the climate control system. In addition, the method includes (b) determining that an expansion valve upstream of the heat exchanger is fully open. Further, the method includes (c) adjusting a speed of air flowing across the coil or a speed of a compressor of the climate control system after (b) based on the determination in (a) to control the superheat of the refrigerant.

A method for operating and controlling a vapor-compression cycle includes providing a system comprising an evaporator with a fan, a compressor, a condenser with a fan, an integrated expander, and a flash tank device with a vapor/liquid two-phase inlet and two outlets wherein a first outlet is a vapor outlet and a second outlet is a liquid outlet, and a metering valve; bringing a vapor-compression cycle up to steady-state at a fixed operating condition; opening the metering valve until the desired compressor suction superheat is achieved; and maintaining the desired degree of superheat by selectively increasing and decreasing superheat by reducing and increasing metering valve flow rate respectively.

Disclosed is an air conditioning system having: a first HVAC assembly comprising an indoor heat exchanger and a fan; a first sensor, configured to sense a first temperature reading, operably coupled to the indoor heat exchanger; a second sensor, configured to sense a second temperature reading, positioned downstream of the first sensor and detached from the indoor heat exchanger; and a system controller configured to activate the fan to deliver airflow across the indoor heat exchanger when the difference between the first temperature reading and the second temperature reading is greater than or equal to a predetermined threshold, the temperate differing being checked when the first HVAC assembly is in an inactive mode and the fan and a compressor operably connected to the first HVAC assembly are in an inactive mode.