An air conditioning system comprising: a plurality of outdoor units; a plurality of indoor units, each communicating with any one of the outdoor units by a first communication method; and a central control device communicating with each of the outdoor units by a second communication method and controlling the outdoor units and the indoor units, characterized in that the air conditioning system is configured such that the one of the outdoor units generates, by using a first address assigned to the one of the outdoor units, a second address of the one of the outdoor units, generates, by using a first address assigned to one or more indoor units connected with the one of the outdoor units among the indoor units, a second address of the one or more indoor units, obtains, from another of the outdoor units, a second address generated by the another of the outdoor units, obtains, from the central control device, a second address of the central control device, checks whether or not there is a duplicate address between the second addresses generated and the second addresses obtained, and, if there is a duplicate address informs a user of information indicating that there is a duplicate address and terminates communication by the second communication method, the first address being used for communication performed using the first communication method and the second address being used for communication performed using the second communication method, and the central control device obtains, from each of the outdoor units, the second addresses of a corresponding one of the outdoor units and each of the indoor units generated by the corresponding one of the outdoor units, and controls an operation of the outdoor units and the indoor units by using the second addresses obtained. a plurality of outdoor units; a plurality of indoor units, each communicating with any one of the outdoor units by a first communication method; and a central control device communicating with each of the outdoor units by a second communication method and controlling the outdoor units and the indoor units, characterized in that the air conditioning system is configured such that the one of the outdoor units generates, by using a first address assigned to the one of the outdoor units, a second address of the one of the outdoor units, generates, by using a first address assigned to one or more indoor units connected with the one of the outdoor units among the indoor units, a second address of the one or more indoor units, obtains, from another of the outdoor units, a second address generated by the another of the outdoor units, obtains, from the central control device, a second address of the central control device, checks whether or not there is a duplicate address between the second addresses generated and the second addresses obtained, and, if there is a duplicate address informs a user of information indicating that there is a duplicate address and terminates communication by the second communication method, the first address being used for communication performed using the first communication method and the second address being used for communication performed using the second communication method, and the central control device obtains, from each of the outdoor units, the second addresses of a corresponding one of the outdoor units and each of the indoor units generated by the corresponding one of the outdoor units, and controls an operation of the outdoor units and the indoor units by using the second addresses obtained.