An HVAC system includes a high-pressure subsystem and a low-pressure subsystem. After determining that refrigerant leak diagnostics should be performed, a controllable valve is closed between a condenser and compressor of the HVAC system. The compressor then operates until a predetermined input refrigerant pressure is reached. After the predetermined input refrigerant pressure is reached, operation of the compressor is stopped. After stopping operation of the compressor and waiting at least a predetermined wait time, the pressure in the low-pressure subsystem of the HVAC system is monitored. A rate of change of the pressure in the low-pressure subsystem is determined. If the rate of change is negative and a magnitude of the rate of change is greater than a threshold value, a leak location is determined to be in the low-pressure subsystem.

An HVAC system includes a high-pressure subsystem and a low-pressure subsystem. After determining that refrigerant leak diagnostics should be performed, a controllable valve is closed between a condenser and compressor of the HVAC system. The compressor then operates until a predetermined input refrigerant pressure is reached. After the predetermined input refrigerant pressure is reached, operation of the compressor is stopped. After stopping operation of the compressor and waiting at least a predetermined wait time, the pressure in the low-pressure subsystem of the HVAC system is monitored. A rate of change of the pressure in the low-pressure subsystem is determined. If the rate of change is negative and a magnitude of the rate of change is greater than a threshold value, a leak location is determined to be in the low-pressure subsystem.

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.

A system is provided and includes a first controller, a non-transitory computer-readable medium and a second controller. The first controller is configured to control operation of at least one compressor circuit including one or more compressors. The non-transitory computer-readable medium is configured to store instructions of a stage profiler for execution by the controller. The instructions include: determining a target system capacity profile for the at least one compressor circuit; determining system stage capacities for stages of the at least one compressor circuit; selecting some of the system stage capacities based on the target system capacity profile to provide an available system capacity profile; generating modulation information based on the available system capacity profile and a load request signal; and controlling operation of the one or more compressors based on the modulation information and according to the available system capacity profile.

A system is provided and includes a first controller, a non-transitory computer-readable medium and a second controller. The first controller is configured to control operation of at least one compressor circuit including one or more compressors. The non-transitory computer-readable medium is configured to store instructions of a stage profiler for execution by the controller. The instructions include: determining a target system capacity profile for the at least one compressor circuit; determining system stage capacities for stages of the at least one compressor circuit; selecting some of the system stage capacities based on the target system capacity profile to provide an available system capacity profile; generating modulation information based on the available system capacity profile and a load request signal; and controlling operation of the one or more compressors based on the modulation information and according to the available system capacity profile.

An air conditioner includes: a fan configured to discharge air cooled by a refrigerant; and at least one processor configured to receive a user input for setting an airflow volume of air to be discharged and a desired temperature, increase a frequency of the compressor to a first critical frequency and maintain the frequency of the compressor as the first critical frequency in response to determining that a temperature difference between an indoor temperature and a desired temperature exceeds the critical temperature difference while controlling the fan to discharge the air with the set airflow volume, determine whether an unsatisfactory condition has occurred, based on at least one cool air-conditioning sensation measurement item while maintaining the first critical frequency, and increase the frequency of the compressor to a second critical frequency to further decrease a current temperature of the air in response to determining that the unsatisfactory situation has occurred.

An air-conditioning apparatus according to the present disclosure includes a heat medium circulation circuit, a heat-source-side device, and a voltage drop device. In the heat medium circulation circuit, a pump, an indoor heat exchanger, and a flow control device are connected by pipes to circulate the heat medium. The pump sends a heat medium that contains water or brine and transfers heat. The indoor heat exchanger causes heat exchange to be performed between the heat medium and an indoor air in an air-conditioned space. The flow control device controls a flow rate of the heat medium in the indoor heat exchanger. The heat-source-side device heats or cools the heat medium before the heat medium is sent to the indoor heat exchanger. The voltage drop device reduces a voltage that is applied to the pump based on a value of a current that is supplied to the pump, in association with a flow rate of the heat medium in the heat medium circulation circuit.

A system for modulating hot gas reheat operation of a heating, ventilation, and/or air conditioning (HVAC) system with multiple compressors, wherein the HVAC system is configured to regulate air provided to multiple zones. The system includes a controller configured to respond to a call for dehumidification in the absence of a call for cooling by sequentially energizing a first compressor of the multiple compressors in a reheat mode of the first compressor, energizing a second compressor of the multiple compressors in a cooling mode of the second compressor, energizing a third compressor of the multiple compressors in a reheat mode of the third compressor initially at full capacity, and energizing a fourth compressor of the multiple compressors in a cooling mode of the fourth compressor.

A system for modulating hot gas reheat operation of a heating, ventilation, and/or air conditioning (HVAC) system with multiple compressors, wherein the HVAC system is configured to regulate air provided to multiple zones. The system includes a controller configured to respond to a call for dehumidification in the absence of a call for cooling by sequentially energizing a first compressor of the multiple compressors in a reheat mode of the first compressor, energizing a second compressor of the multiple compressors in a cooling mode of the second compressor, energizing a third compressor of the multiple compressors in a reheat mode of the third compressor initially at full capacity, and energizing a fourth compressor of the multiple compressors in a cooling mode of the fourth compressor.

The present disclosure presents techniques for improving operational efficiency of climate control systems. A climate control system may include climate control equipment, a sensor that measures temperature in a building, and a control system that controls operation of the equipment using a first temperature schedule, which associates each time step with a temperature setpoint, when the building is occupied. When not occupied, the control system determines an expected return time based on historical occupancy data associated with the building, determines the temperature setpoint associated with the expected return time, determines candidate schedules each expected to result in the inside air temperature meeting the temperature setpoint, determines efficiency metrics each associated with one of the candidates based on historical performance data resulting from previous operation of the climate control system, and controls operation of the equipment based on a second temperature schedule selected from the candidates based on associated efficiency metrics.