Diagnosis control method of air conditioner

A diagnosis control method of an air conditioner including a plurality of indoor units, the diagnosis control method comprising:

• receiving a test run command or a self-diagnosis command for diagnosis of the air conditioner;
• performing a first test run to diagnose an assembly state of the air conditioner;
• performing a second test run to diagnose pipe connection of the air conditioner and an amount of refrigerant in the air conditioner;
• changing an operation frequency of a compressor so as to correspond to the number of indoor units test running during operation of the compressor;
• and
• performing a determination including diagnosing a state of the air conditioner based on operation results of the first test run and the second test run and displaying the diagnosis result through a display device provided at an indoor unit of the air conditioner,
• wherein the performing the second test run further comprises determining, if a difference (Teva_in)−(Teva_in+1) between an inlet temperature (Teva_in) of an indoor heat exchanger of an indoor unit before a compressor of an outdoor unit is operated and an inlet temperature (Teva_in+1) of the indoor heat exchanger of the indoor unit after the compressor of the outdoor unit is operated is less than a predetermined reference value, that a pipe connection error has occurred between the outdoor unit and the indoor unit.