Air conditioning (100), featuring: a large number of
air conditioning units (1A, 1B), each comprising an outdoor unit (10A, 10B), an indoor unit (20A, 20B) and a
remote control (30A, 30B); and a
transmission line (3) through which the multiple
air conditioning units (1A, 1B) are connected to each other, where each of the outdoor units (10A, 10B) includes: a
communication unit (111A, 111B) designed to send and receive a
signal, a
repeater (112A, 112B) designed to
relay a
signal of a set frequency, and a memory (115A, 115B) designed to store
class information of the
repeater (112A, 112B), wherein the
class information includes a set frequency with which the
repeater (112A, 112B) is compatible, wherein the
remote control (30A) of the one air conditioner (1A) of the multiple air conditioners (1A, 1B) is designed to capture the
class information of the repeater (112A) of the one air conditioner (1A) stored in the memory (115A) of the one air conditioner (1A), wherein the indoor unit (20B) of the other air conditioner (1B) is designed to capture the class information of the repeater (112B) of the other air conditioner (1B) stored in the memory (115B) of the other air conditioner (1B), wherein, in a case where, based on the class information, a set frequency with which the repeater (112A) of one air conditioner (1A) is compatible and a set frequency with which the repeater (112B) of the other air conditioner (1B) is compatible match, the
remote control (30A) of one air conditioner (1A) and the indoor unit (20B) of the other air conditioner (1B) are designed to perform communication using a
signal of the set frequency so matching.