| 摘要 |
An air-conditioning apparatus (1) uses carbon dioxide as a refrigerant, and has a two-stage compression-type compression mechanism (2), a heat source-side heat exchanger (4), an expansion mechanism (5), a usage-side heat exchanger (6), a switching mechanism (3), and a first second-stage injection tube (18c). In the air-conditioning apparatus (1), refrigerant is prevented from returning to a second-stage compression element (2d) through the first second-stage injection tube (18c), at least during the beginning of a reverse cycle defrosting operation for defrosting the heat source-side heat exchanger (4) by switching the switching mechanism (3) to a cooling operation state.
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