To provide a heat accumulating air conditioner which is capable of cooling/ heating/defrosting/ventilating at a hot or cold sever climate environment by providing two and more expansion valves on a heat accumulating unit and further providing a heat exchanger in the heat accumulating unit, an outdoor unit and an indoor unit respectively.

In a winter cycle, a heating medium is circulated in the arrow 24 direction. When the outside air temperature is high and frost is not deposited on a heat exchanger 27 of an outside unit 4, heart accumulation is carried out. When both heat accumulation and heating are carried out at the same time, an expansion valve 9 is constituted while an expansion valve 6 is opened. When the outside air temperature is low and frost is produced on the heat exchanger 27, heating is carried out with the heat of a latent heat accumulation material 30. At that time, the heating medium is circulated in the arrow 24 direction. The expansion valve 6 is constricted while the expansion valve 9 is opened. In a summer cycle, the heating medium is circulated in the arrow 10 direction. When both heat accumulation and cooling are carried out at the same time, the expansion valve 9 is constituted while the expansion valve 6 is opened. When only heat accumulation is carried out, the expansion valve 9 is constituted while the expansion valve is opened as well.