An outdoor unit of an air-conditioning apparatus includes an outdoor unit main body, a compressor, an outdoor heat exchanger, an outdoor fan, an outdoor air temperature detection unit, and a control unit. The control unit stores an outdoor air temperature that is detected when the outdoor unit main body receives an operation stop signal, a temperature determination unit configured to determine whether the outdoor air temperature stored in the storage unit is less than a temperature threshold value when the outdoor unit main body receives an operation start signal, and an operation timing setting unit configured to select an operation mode of the compressor based on an outdoor air temperature detected by the outdoor air temperature detection unit after operation of the outdoor fan is resumed in a case where the temperature determination unit determines that the outdoor air temperature is less than the temperature threshold value.

An arrangement of multiple environmental control systems for a multi-unit structure has a first environmental control system installed in a first unit, a second environmental control system installed in a second unit, a system monitor in communication with each of the environmental control systems and a firewall. Each environmental control system has a control unit coupled to the system monitor through the firewall that prevents unauthorized devices from accessing the respective control unit and a HVAC system device coupled to the respective control unit through the firewall. For each unit, a local user device that is located inside the unit is coupled to the control unit through a local communication interface, and an external user device that is located outside the unit communicates with the control unit through the firewall.

An arrangement of multiple environmental control systems for a multi-unit structure has a first environmental control system installed in a first unit, a second environmental control system installed in a second unit, a system monitor in communication with each of the environmental control systems and a firewall. Each environmental control system has a control unit coupled to the system monitor through the firewall that prevents unauthorized devices from accessing the respective control unit and a HVAC system device coupled to the respective control unit through the firewall. For each unit, a local user device that is located inside the unit is coupled to the control unit through a local communication interface, and an external user device that is located outside the unit communicates with the control unit through the firewall.

An outdoor unit includes: two fan motors that respectively drive two outdoor fans arranged one above the other; a controller including a fan motor power supply capable of separately supplying power to each of the two fan motors connected to two fan motor connectors; and an electrical component temperature sensor that measures temperatures of electrical components. The controller includes a control circuitry that detects which of the two fan motor connectors each of the two fan motors is connected to and supplies power in such a way as to drive the upper one of the outdoor fans based on a result of the detection at the time of single-fan operation. The detection is performed based on comparison between temperatures of the electrical components at the start of the single-fan operation and temperatures of the electrical components after a set time has elapsed since the start of the single-fan operation.

A heating, ventilation, and/or air conditioning (HVAC) system includes a compressor, a fan, an inverter configured to drive operation of the compressor, and a controller communicatively coupled to the fan and the inverter. The controller includes a tangible, non-transitory, computer-readable medium with computer-executable instructions that, when executed by processor circuitry, are configured to cause the processor circuitry to determine an operating parameter of the fan in response to an interruption in receiving communication signals from the inverter and operate the fan based on the operating parameter during the interruption.

A heating, ventilation, and/or air conditioning (HVAC) system includes a compressor, a fan, an inverter configured to drive operation of the compressor, and a controller communicatively coupled to the fan and the inverter. The controller includes a tangible, non-transitory, computer-readable medium with computer-executable instructions that, when executed by processor circuitry, are configured to cause the processor circuitry to determine an operating parameter of the fan in response to an interruption in receiving communication signals from the inverter and operate the fan based on the operating parameter during the interruption.

A heating, ventilation and air-conditioning (HVAC) system is provided. The HVAC system includes indoor and outdoor units to condition air of a space, an indoor heat exchanger by which the indoor and outdoor units thermally interact, temperature sensors operably disposed at least at the indoor heat exchanger and in the space and a controller operably coupled to the indoor and outdoor units and configured to control operations of the indoor and outdoor units in accordance with readings of the temperature sensors by reference to space-dew point temperature relationship tables.

A refrigeration cycle, an air conditioning system, and a method for controlling a refrigeration cycle are provided. The refrigeration cycle includes an outdoor unit, an indoor unit, a controller, and an inverter. The controller controls a compressor and an outdoor fan of the air conditioning system so as to minimize a total electric power consumption of the air conditioning system. The inverter controls the outdoor fan in a rotation state predicted from a capacity demand in an air conditioning space depending on an operation mode and sensor values. The controller predicts the capacity demand and controls a rotation rate of the outdoor fan based on a prediction of the capacity demand.

A refrigeration cycle, an air conditioning system, and a method for controlling a refrigeration cycle are provided. The refrigeration cycle includes an outdoor unit, an indoor unit, a controller, and an inverter. The controller controls a compressor and an outdoor fan of the air conditioning system so as to minimize a total electric power consumption of the air conditioning system. The inverter controls the outdoor fan in a rotation state predicted from a capacity demand in an air conditioning space depending on an operation mode and sensor values. The controller predicts the capacity demand and controls a rotation rate of the outdoor fan based on a prediction of the capacity demand.

An air conditioning system with precisely controlled dehumidification functions is disclosed. The air conditioning system comprises an indoor air handling system comprising a primary heat exchanger and a secondary heat exchanger. The indoor air handling system can be coupled to an outdoor unit comprising a compressor and an outdoor heat exchanger. When a controller system receives a measured humidity that exceeds a set humidity, the controller system can increase the cooling capacity of the air conditioning system to meet a set temperature. Once the set temperature is met, the controller system can switch to a dehumidification mode wherein the primary heat exchanger is cooled and the secondary heat exchanger is activated. When the measured temperature exceeds the set temperature, the controller system can switch from the dehumidification mode back to cooling mode.