An air conditioning system comprising: at least one air conditioner; a management server configured to analyze data relating to the air conditioner received from the air conditioner at a predetermined time interval and to diagnose an operation state of the air conditioner; and a database configured to collect the data relating to the air conditioner; wherein the management server comprises: a memory to store the data relating to the air conditioner, a communication unit configured to receive the data relating to the air conditioner; a main controller configured to store the data relating to the air conditioner in the memory; and a diagnostic unit configured to: analyze the data relating to the air conditioner; and determine the operation state of the air conditioner in real time; characterized in that the diagnostic unit is further configured to: calculate a coefficient of performance and a heat balance of the air conditioner for a predetermined period based on the data relating to the air conditioner accumulated during the predetermined period; calculate the data on performance and efficiency of the air conditioner to determine performance deterioration of the air conditioner based on at least one of the calculated COP and heat balance, determine one of a normal state, an anomalous state and a malfunction state of the air conditioner as the operation state from the data relating to the air conditioner accumulated during the predetermined period; and derive a countermeasure based on the determined operation state of the air conditioner. at least one air conditioner; a management server configured to analyze data relating to the air conditioner received from the air conditioner at a predetermined time interval and to diagnose an operation state of the air conditioner; and a database configured to collect the data relating to the air conditioner; wherein the management server comprises: a memory to store the data relating to the air conditioner, a communication unit configured to receive the data relating to the air conditioner; a main controller configured to store the data relating to the air conditioner in the memory; and a diagnostic unit configured to: analyze the data relating to the air conditioner; and determine the operation state of the air conditioner in real time; characterized in that the diagnostic unit is further configured to: calculate a coefficient of performance and a heat balance of the air conditioner for a predetermined period based on the data relating to the air conditioner accumulated during the predetermined period; calculate the data on performance and efficiency of the air conditioner to determine performance deterioration of the air conditioner based on at least one of the calculated COP and heat balance, determine one of a normal state, an anomalous state and a malfunction state of the air conditioner as the operation state from the data relating to the air conditioner accumulated during the predetermined period; and derive a countermeasure based on the determined operation state of the air conditioner. a memory to store the data relating to the air conditioner, a communication unit configured to receive the data relating to the air conditioner; a main controller configured to store the data relating to the air conditioner in the memory; and a diagnostic unit configured to: analyze the data relating to the air conditioner; and determine the operation state of the air conditioner in real time; analyze the data relating to the air conditioner; and determine the operation state of the air conditioner in real time; characterized in that the diagnostic unit is further configured to: calculate a coefficient of performance and a heat balance of the air conditioner for a predetermined period based on the data relating to the air conditioner accumulated during the predetermined period; calculate the data on performance and efficiency of the air conditioner to determine performance deterioration of the air conditioner based on at least one of the calculated COP and heat balance, determine one of a normal state, an anomalous state and a malfunction state of the air conditioner as the operation state from the data relating to the air conditioner accumulated during the predetermined period; and derive a countermeasure based on the determined operation state of the air conditioner. calculate a coefficient of performance and a heat balance of the air conditioner for a predetermined period based on the data relating to the air conditioner accumulated during the predetermined period; calculate the data on performance and efficiency of the air conditioner to determine performance deterioration of the air conditioner based on at least one of the calculated COP and heat balance, determine one of a normal state, an anomalous state and a malfunction state of the air conditioner as the operation state from the data relating to the air conditioner accumulated during the predetermined period; and derive a countermeasure based on the determined operation state of the air conditioner.