The invention provides a
defrosting control method and
system and an air conditioner. The
defrosting control method comprises the following steps that a
system parameter is detected by the air conditioner under a heating mode; if the
system parameter reaches the preset
defrosting condition, a stop valve is controlled to close, and an
electric heating piece works; and the heat accumulator temperatures of the time when the electric the heating piece
stars working and during first preset duration are respectively recorded to be T0 and Ti, if the
temperature difference of the heat accumulator is not larger than the preset
temperature difference, the
electric heating piece is controlled to stop working, the stop valve is started, a four-way valve is reversed to enable the air conditioner to defrost under a refrigerating mode, or else, defrosting is finished. According to the defrosting method provided by the invention, the air conditioner defrosts under the refrigerating mode, the good defrosting effect and good
heating effect are ensured, and using comfort of a user is promoted; and when the temperature of the heat accumulator slowly rises, and heat of a heat storage
assembly cannot meet the defrosting requirements of the air conditioner under the heating mode, the four-way valve is reversed to enable the air conditioner to defrost under the refrigerating mode, normal defrosting of the air conditioner is ensured, and the using satisfaction degree of the user is improved.