An air conditioner comprising: one or more indoor units (200 to 203), each indoor unit comprising: an indoor temperature measuring unit configured to measure an indoor air temperature, an indoor heat exchanger, a heat exchanger temperature measuring unit configured to measure an inlet temperature and an outlet temperature of the indoor heat exchanger, and a cooling fan configured to blow cold air generated in the indoor heat exchanger; an outdoor temperature measuring unit configured to measure an outdoor air temperature; a compressor connected to the indoor heat exchanger; and a processor configured to: receive a trial operation start command for testing whether the air conditioner is normally operated, operate the cooling fan first for a predetermined time before the indoor heat exchanger is operated, determine whether the cooling fan is operating normally using a feedback signal transmitted from the heat exchanger temperature measuring unit, operate the compressor, determine a reference superheat degree based on a correlation obtained in advance using the indoor air temperature, the outdoor air temperature, and a measured superheat degree, obtain a difference between the inlet temperature and the outlet temperature of the indoor heat exchanger, compare the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger and the reference superheat degree, determine that the circulation amount of the refrigerant of the air conditioner is normal when the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger is smaller than or equal to the reference superheat degree, and determine that the circulation amount of the refrigerant of the air conditioner is abnormal when the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger is larger than the reference superheat degree. one or more indoor units (200 to 203), each indoor unit comprising: an indoor temperature measuring unit configured to measure an indoor air temperature, an indoor heat exchanger, a heat exchanger temperature measuring unit configured to measure an inlet temperature and an outlet temperature of the indoor heat exchanger, and a cooling fan configured to blow cold air generated in the indoor heat exchanger; an indoor temperature measuring unit configured to measure an indoor air temperature, an indoor heat exchanger, a heat exchanger temperature measuring unit configured to measure an inlet temperature and an outlet temperature of the indoor heat exchanger, and a cooling fan configured to blow cold air generated in the indoor heat exchanger; an outdoor temperature measuring unit configured to measure an outdoor air temperature; a compressor connected to the indoor heat exchanger; and a processor configured to: receive a trial operation start command for testing whether the air conditioner is normally operated, operate the cooling fan first for a predetermined time before the indoor heat exchanger is operated, determine whether the cooling fan is operating normally using a feedback signal transmitted from the heat exchanger temperature measuring unit, operate the compressor, determine a reference superheat degree based on a correlation obtained in advance using the indoor air temperature, the outdoor air temperature, and a measured superheat degree, obtain a difference between the inlet temperature and the outlet temperature of the indoor heat exchanger, compare the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger and the reference superheat degree, determine that the circulation amount of the refrigerant of the air conditioner is normal when the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger is smaller than or equal to the reference superheat degree, and determine that the circulation amount of the refrigerant of the air conditioner is abnormal when the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger is larger than the reference superheat degree. receive a trial operation start command for testing whether the air conditioner is normally operated, operate the cooling fan first for a predetermined time before the indoor heat exchanger is operated, determine whether the cooling fan is operating normally using a feedback signal transmitted from the heat exchanger temperature measuring unit, operate the compressor, determine a reference superheat degree based on a correlation obtained in advance using the indoor air temperature, the outdoor air temperature, and a measured superheat degree, obtain a difference between the inlet temperature and the outlet temperature of the indoor heat exchanger, compare the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger and the reference superheat degree, determine that the circulation amount of the refrigerant of the air conditioner is normal when the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger is smaller than or equal to the reference superheat degree, and determine that the circulation amount of the refrigerant of the air conditioner is abnormal when the difference between the inlet temperature and the outlet temperature of the indoor heat exchanger is larger than the reference superheat degree.