A method of controlling an air conditioner including a compressor, an outdoor heat exchanger, an expansion valve and an indoor unit, includes detecting an indoor temperature and an outdoor temperature and checking an indoor load and an outdoor load when an operation command is input, determining an operation frequency of the compressor and a degree of opening of the expansion valve based on the checked indoor load and the outdoor load, driving the compressor at the determined operation frequency and opening the expansion valve to the determined degree of opening, thereby supplying a refrigerant to an indoor heat exchanger having a first cooling panel and a second cooling panel disposed parallel to each other, controlling a rate of rotation of each of the indoor fans based on the operation frequency of the compressor and the degree of opening of the expansion valve.

A controller of an inverter control apparatus includes an A/D conversion unit that performs digital conversion of an input signal when a signal for either an A/D converter start trigger or an A/D converter start trigger is input thereinto; a first inverter control unit that generates the A/D converter start trigger which starts the A/D conversion unit, based on A/D converter start timing information and a first carrier signal; a second inverter control unit that generates the A/D converter start trigger which starts the A/D conversion unit, based on A/D converter start timing information and a second carrier signal; and an A/D start factor selection unit that receives either the A/D converter start trigger or the A/D converter start trigger and selects an A/D start factor at a predetermined period timing of an operation period of the first carrier signal and the second carrier signal.

A system and method of heat exchanger freeze protection for an HVAC system by operating an indoor unit assembly and an outdoor unit assembly in a cooling mode and operating a fan at an initial airflow, operating a temperature sensor to measure a temperature value of a heat exchanger, at the expiration of a first predetermined time period, determining whether the temperature value is less than or equal to a first temperature preset value, determining whether a current airflow multiplier is equal to a maximum airflow multiplier limit, increasing the current airflow by an airflow offset multiplier if the current airflow multiplier is less than or equal to the maximum airflow multiplier limit and the temperature value is less than or equal to the first temperature preset, and operating the fan at an increased airflow to move more air across the heat exchanger.

A method for operating a heat pump (20; 300) includes operating in a cooling mode wherein heat is absorbed by refrigerant in the indoor heat exchanger (26) and rejected by refrigerant in the outdoor heat exchanger (24). The heat pump switches to operation in a heating mode wherein heat is rejected by refrigerant in the indoor heat exchanger, heat is absorbed by refrigerant in the outdoor heat exchanger, and there is an ejector (60) motive flow and ejector secondary flow. In the heating mode a refrigerant pressure (P.sub.H) or temperature (T.sub.L) is measured and, responsive to the measured refrigerant pressure or temperature, at least one of a fan speed is changed and a needle (132) of the ejector is actuated.

An air-conditioning apparatus is capable of suppressing refrigerant flow noise regardless the refrigerant state of an inlet of an expansion mechanism. In parallel to a flow control valve, an opening and closing valve that opens and closes a refrigerant passage and an expansion mechanism having porous bodies capable of passing a refrigerant therethrough are connected in series with each other. In a heating mode, in the case where a controller stops an operation of one or more of a plurality of indoor units and causes the other indoor unit(s) to operate, the flow control valve of the stopped indoor unit is fully closed and the opening and closing valve of the stopped indoor unit is opened.

A refrigeration cycle system is capable of reducing an amount of information required to be specified in advance, reducing a computational processing load, reflecting differences in actual installation conditions, and speeding up stabilization of an operational state in which the total amount of required input energy is reduced. A refrigeration cycle system is provided with a plurality of actuators, including outdoor fan motors, compressors, indoor fan motors, and the like for causing a refrigerant circuit to carry out a refrigeration cycle. A control unit obtains the slope at the current evaporation temperature and/or the current condensing temperature on a graph of the function between the actuators and the evaporation temperature or the condensing temperature, and updates the value of the target evaporation temperature and/or the target condensing temperature so that the sum of the input energy to the actuators is less that the current level.

An indoor unit includes: a casing; a heat exchanger through which a flammable refrigerant flows; a fan; a detection sensor detecting a leak of the flammable refrigerant; a warning device emitting a warning about a leak of the flammable refrigerant; a control unit controlling operations of the fan and the warning device; and an operation device inputting stop commands for the fan and the warning device to the control unit based on its manual operation. Upon detection of a leak of the flammable refrigerant by the detection sensor, the control unit starts up the fan on condition that the fan is at a stop, starts up the warning device, disregards a stop command for the fan by the operation device, and permits a stop command for the warning device by the operation device. As a result, a user is enabled to arbitrarily stop a warning started based on occurrence of a refrigerant leak.

A system for charging an outdoor unit with refrigerant includes a sensor configured to measure a refrigerant concentration and a user device configured to receive the measured refrigerant concentration. The system includes that the user device is configured to, in response to the measured refrigerant concentration exceeding a threshold, generate and display an alert on a user interface of the user device indicating the measured refrigerant concentration exceeds the threshold.

A high-efficiency HVAC system and method of operation, for use in a house or building, having a plurality of components, including flexible, plastic duct tubing forming supply pipes that connect an air handler and a plurality of zones to deliver supply air to the zones and return pipes that connect the air handler and the zones to re-circulate return air; the air handler having a fan assembly powered by a variable blower motor to blow supply air to the zones; a heat pump having a variable compressor powered by a variable compressor motor to direct a working fluid to and from the air handler and a variable fan motor that rotates a fan blade within the heat pump; and a circuit control system for adjusting the variable compressor motor and the variable fan motor in the heat pump and the variable blower motor in the air handler.

A system includes a condensing unit, a valve, and a unit cooler. The condensing unit is configured to condense refrigerant. The valve is configured to control the flow of the refrigerant from the condensing unit to the unit cooler. The unit cooler is configured to operate in a refrigeration mode and a stir-cycle mode. The unit cooler is configured to operate at a first speed during the refrigeration mode and at a second speed for a first period of time and at a third speed for a second period of time during the stir-cycle mode. The second speed is slower than the first speed and the third speed is slower than the second speed. Electric power is supplied to the unit cooler throughout the refrigeration mode and the stir-cycle mode.