from becoming too low which would otherwise result in degraded thermal comfort if all the indoor units are operating under the heat recovery and dehumidifying condition then the refrigerant will flow as schematically illustrated in fig6 under the normally heat recovery and dehumidifying condition the respective components in the outdoor unit 01 will be connected the valves will be opened and closed and the heat exchangers will function in substantially the same way as they are under the normally heat recovery condition so a repeated description thereof will be omitted here in the indoor units 02 and 02 u2032 the first electronic expansion valves 15 are fully opened and the second indoor electronic expansion valves 17 are throttling for lower pressure the first indoor heat exchangers 16 are condensers which discharge heat to heat the outgoing air through the refrigerant so as to improve the temperature of outgoing air the second indoor heat exchangers 18 are evaporators which lower the temperature of and dehumidify the air the refrigerant after the condensation and heat exchange by the outdoor heat exchanger 5 and the high pressure liquid refrigerant after condensation and heat exchange by the first indoor heat exchangers 16 meet at the fourth manifold pipe 05 then flow through the second indoor electronic expansion valves 17 the second indoor heat exchangers 18 the second manifold pipe 052 and the d and c ends of four way branch 4 sequentially and thereafter enter the vapor liquid separator 7 thus completing the refrigeration loop of the refrigerant as illustrated in fig7 there is a schematic.