Abstract: An air conditioning apparatus in which one outdoor unit is connected to several indoor units through respective refrigerant tubes and signal conductors. The outdoor unit has compressors for discharging refrigerant and an outdoor heat exchanger. Each outdoor unit has an indoor heat exchanger and an indoor heat exchanger temperature sensor. When an operating device signals a check node, the compressors are stopped for a predetermined time period. Then the compressors are operated to sequentially discharge refrigerant to each indoor unit. A checking device then monitors the signal conductors of each indoor unit for a signal indicating a certain temperature condition. Based on the signals received, the checking device determines whether the indoor units are properly connected to the outdoor unit.

Abstract: An outdoor unit includes at least two compressors and an outdoor heat exchanger commonly coupled thereto. An indoor unit is coupled to the outdoor unit to form a refrigeration cycle. The indoor unit includes at least an indoor heat exchanger and means for outputting required capacity data in accordance with an air-conditioning load with respect to the indoor heat exchanger. A pressure detector detects the high-pressure-side pressure of the refrigeration cycle. A first control section controls the number of compressors to be driven. The first control section sequentially starts the two compressors so as to control the compressors in a parallel operation state when the number of compressors to be driven is controlled to be two.