Abstract: An air conditioning system having a cooling mode and a free-cooling mode. The system having a refrigeration circuit having a compressor and a pump; a suction pressure sensor for measuring a suction pressure of the compressor; a discharge pressure sensor for measuring a discharge pressure of the compressor; a controller for selectively operating in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operating in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump; and a recover-refrigerant sequence resident on the controller, the recover-refrigerant sequence being configured to pump the refrigerant in a portion of the refrigeration circuit not used in the free-cooling mode to remaining portions of the refrigeration circuit used in the free-cooling mode when the controller switches from the cooling mode to the free-cooling mode.

Abstract: An air conditioning system having a cooling mode and a free-cooling mode. The system having a refrigeration circuit having a compressor and a pump; a suction pressure sensor for measuring a suction pressure of the compressor; a discharge pressure sensor for measuring a discharge pressure of the compressor; a controller for selectively operating in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operating in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump; and a recover-refrigerant sequence resident on the controller, the recover-refrigerant sequence being configured to pump the refrigerant in a portion of the refrigeration circuit not used in the free-cooling mode to remaining portions of the refrigeration circuit used in the free-cooling mode when the controller switches from the cooling mode to the free-cooling mode.

Abstract: A method of controlling an air conditioning system having a cooling mode and a free-cooling mode, including activating the air conditioning system; measuring a first temperature of ambient air surrounding a condenser, measuring a second temperature of the working fluid; calculating a difference between the first and second temperatures; and comparing the difference to a predetermined value, wherein if the difference is greater than or equal to the predetermined value the free-cooling mode is activated, and wherein if the difference is less than the predetermined value the cooling mode is activated.

Abstract: An air conditioning system having a cooling mode and a free-cooling mode is provided. The system includes a refrigeration circuit, two pressure sensors, a controller, and a pump starting sequence resident on the controller. The refrigeration circuit includes a compressor and a pump. The first pressure sensor is at an inlet of the pump, while the second pressure sensor is at an outlet of the pump. The controller selectively operates in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via the compressor or operates in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump. The pump starting sequence cycles the pump between an on state and an off state based at least upon a differential pressure determined by the controller from pressures detected by the pressure sensors.

Abstract: A method of controlling an air conditioning system having a cooling mode and a free-cooling mode, including activating the air conditioning system; measuring a first temperature of ambient air surrounding a condenser; measuring a second temperature of the working fluid; calculating a difference between the first and second temperatures; and comparing the difference to a predetermined value, wherein if the difference is greater than or equal to the predetermined value the free-cooling mode is activated, and wherein if the difference is less than the predetermined value the cooling mode is activated.

Abstract: An air conditioning system having a cooling mode and a free-cooling mode. The system includes a refrigeration circuit have a compressor, a pump, an expansion device having a variable opening, and a controller. The controller selectively operates the system in the cooling mode by circulating and compressing a refrigerant through the refrigeration circuit via said compressor, or in the free-cooling mode by circulating the refrigerant through the refrigeration circuit via the pump. A free-cooling limitation and variation sequence resides on said controller and varies the variable opening based at least upon a differential temperature.