Air-conditioning apparatus and method of determining operation condition

A method of determining an operation condition, the method being performed by an air-conditioning apparatus including a plurality of indoor units and a memory, the plurality of indoor units each including a suction temperature sensor detecting a suction temperature that is a temperature of air sucked into the indoor unit from an air-conditioning target space, the plurality of indoor units each individually conditioning the air in the air-conditioning target space by using the suction temperature and a preset temperature, the method comprising:

• storing detection values of the suction temperature sensors in time series in the memory;
• measuring, for each of the plurality of indoor units, a preset temperature arrival period it takes for the suction temperature to reach the preset temperature for the air-conditioning target space after start of a thermo-on state or a thermo-off state;
• calculating, for each of the plurality of indoor units, a temperature change slope representing a change in the suction temperature for the preset temperature arrival period;
• and
• comparing the temperature change slope of each of the plurality of indoor units with a determination threshold to determine, as an abnormal indoor unit, the indoor unit having the temperature change slope greater than the determination threshold.