| 摘要 |
Two outdoor units (2A, 2B) and three indoor units (3A, 3B, 3C) are connected to a main liquid line (7L) and a main gas line (7G) in series and parallel, respectively. Lubricant balancing mechanisms (9A, 9B) are provided on the respective outdoor units (2A, 2B) for guiding excessive lubricant stored in a lubricant reservoir (91) provided on the discharge side of a compressor (21) of one of the two outdoor units to the suction side of the compressor (21) of the other of the two units. At the time of cooling operation, respective gas by-pass passageways (95, 96) and respective lubricant balancing by-pass pipes (93, 94) are controlled to be opened and/or closed such that lubricant flows alternately between the respective outdoor units (2A, 2B). At the time of heating operation, the respective oil balancing by-pass pipes (93, 94) are controlled to be opened and/or closed such that lubricant flows alternately between the respective outdoor units (2A, 2B) with the downstream side of the lubricant balancing mechanisms (9A, 9B) being maintained at a low pressure to thereby uniformize lubricant.
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