Air conditioner and control method thereof

An air conditioner, comprising:

• an outdoor unit including an outdoor heat exchanger, a compressor, an outdoor expansion valve, and a four-way valve;
• an indoor unit, to be installed indoors, including an indoor heat exchanger and an indoor expansion valve;
• a liquid pipe, connectable to the outdoor unit and the indoor unit, formed to allow a refrigerant in a liquid state to flow therethrough;
• a gas pipe, connectable to the outdoor unit and the indoor unit and formed to allow the refrigerant in a gaseous state to flow therethrough;
• a shutoff device including a first shutoff valve opening and closing the liquid pipe and a second shutoff valve opening and closing the gas pipe;
• a leakage sensor configured to detect whether a refrigerant leakage occurs;
• and
• a controller, configured to control driving of the outdoor unit and the indoor unit, or to control opening and closing of the first shutoff valve and the second shutoff valve,
• wherein the controller, based on the leakage sensor detecting the refrigerant leakage is occurring in a predetermined section, is configured to:
• close the first shutoff valve,
• control the four-way valve to operate a circulation direction of the refrigerant in a heating operation,
• operate the compressor and the indoor heat exchanger and condense at least a portion of the refrigerant flowing in the indoor unit, the liquid pipe, and the gas pipe,
• recover the condensed refrigerant to the indoor unit and the liquid pipe, and
• close the second shutoff valve based on satisfying a preset condition.