PURPOSE: To reduce the number of times of unnecessary starting and stopping of a compressor and improve the reliability by with holding actions on frost proof decision from operating for a certain time when the selected operating units are decreased from a set of a first and a second compressors and a set of a first and a second heat exchangers on the indoor side.
CONSTITUTION: When a first and a second of a set of heat exchangers 7, 8 on the indoor side are both selected, a first and a second of a set of compressors 1, 2 are both operated, a blower 14 is set to give a standard air quantity, and a first and a second of a set of solenoid valves 19, 20 open. Then selection of only the first indoor side heat exchanger 7, stopping the use of the second indoor side heat exchanger 8, leaves the first compressor 1 to operate and the first solenoid valve 19 to be open but stops the second compressor 2 from operating and causes the second solenoid valve 20 to close and simultaneously sets a timer counting in order not to allow a decision means to operate before the timer finishes counting. After the timer has finished counting, the frost proof decision is made to operate.
NAKAMURA SETSU
ISHIKAWA KOJI
IGARASHI YOSHINOBU
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