An air conditioning system comprising: an outdoor unit including a compressor and an outdoor heat exchanger; an indoor unit (410, 420) including an indoor heat exchanger; a distribution unit for connecting the outdoor unit with the indoor unit (410, 420) and distributing refrigerant to the indoor unit (410, 420); a flow switching unit for guiding the refrigerant discharged to the outdoor heat exchanger or the indoor unit (410, 420); and connection pipes for connecting the outdoor unit with the distribution unit and including a liquid pipe, through which liquid refrigerant flows, a low-pressure pipe, through which first gaseous refrigerant flows, and a high-pressure pipe, through which second gaseous refrigerant flows, wherein the distribution unit includes: a supercooling heat exchanger (320, 330) disposed between the liquid pipe and the indoor unit (410, 420) and through which liquid refrigerant passing through the liquid pipe flows; a supercooling expansion device connected to the supercooling heat exchanger (320, 330) to adjust an opening degree such that a degree of supercooling of the liquid refrigerant passing through the supercooling heat exchanger (320, 330) increases or decreases; a first liquid pipe branching the liquid refrigerant through the liquid pipe into the supercooling heat exchanger (320, 330) and the supercooling expansion device; characterised by a temperature sensor for sensing a temperature of the liquid refrigerant introduced into the distribution unit through the first liquid pipe; a pressure sensor for sensing pressure of the liquid refrigerant introduced into the distribution unit through the first liquid pipe; and a controller for controlling the opening degree of the supercooling expansion device based on information sensed by the temperature sensor and the pressure sensor. an outdoor unit including a compressor and an outdoor heat exchanger; an indoor unit (410, 420) including an indoor heat exchanger; a distribution unit for connecting the outdoor unit with the indoor unit (410, 420) and distributing refrigerant to the indoor unit (410, 420); a flow switching unit for guiding the refrigerant discharged to the outdoor heat exchanger or the indoor unit (410, 420); and connection pipes for connecting the outdoor unit with the distribution unit and including a liquid pipe, through which liquid refrigerant flows, a low-pressure pipe, through which first gaseous refrigerant flows, and a high-pressure pipe, through which second gaseous refrigerant flows, wherein the distribution unit includes: a supercooling heat exchanger (320, 330) disposed between the liquid pipe and the indoor unit (410, 420) and through which liquid refrigerant passing through the liquid pipe flows; a supercooling expansion device connected to the supercooling heat exchanger (320, 330) to adjust an opening degree such that a degree of supercooling of the liquid refrigerant passing through the supercooling heat exchanger (320, 330) increases or decreases; a first liquid pipe branching the liquid refrigerant through the liquid pipe into the supercooling heat exchanger (320, 330) and the supercooling expansion device; characterised by a temperature sensor for sensing a temperature of the liquid refrigerant introduced into the distribution unit through the first liquid pipe; a pressure sensor for sensing pressure of the liquid refrigerant introduced into the distribution unit through the first liquid pipe; and a controller for controlling the opening degree of the supercooling expansion device based on information sensed by the temperature sensor and the pressure sensor. a supercooling heat exchanger (320, 330) disposed between the liquid pipe and the indoor unit (410, 420) and through which liquid refrigerant passing through the liquid pipe flows; a supercooling expansion device connected to the supercooling heat exchanger (320, 330) to adjust an opening degree such that a degree of supercooling of the liquid refrigerant passing through the supercooling heat exchanger (320, 330) increases or decreases; a first liquid pipe branching the liquid refrigerant through the liquid pipe into the supercooling heat exchanger (320, 330) and the supercooling expansion device; characterised by a temperature sensor for sensing a temperature of the liquid refrigerant introduced into the distribution unit through the first liquid pipe; a pressure sensor for sensing pressure of the liquid refrigerant introduced into the distribution unit through the first liquid pipe; and a controller for controlling the opening degree of the supercooling expansion device based on information sensed by the temperature sensor and the pressure sensor.