Air conditioner including a bypass pipeline for a defrosting operation

An air conditioner, comprising:

• an outdoor unit having a compressor that pressurizes and discharges a refrigerant, a plurality of outdoor heat exchangers that exchange heat between outside air and the refrigerant, and first channel switching means that switches a channel on the basis of an operation form;
• a plurality of indoor units, each having an indoor heat exchanger that exchanges heat between air in a space to be air-conditioned and the refrigerant and indoor flow-rate control means, both being connected by a pipeline so as to constitute a refrigerant circuit, wherein
• a bypass pipeline that divides the refrigerant discharged from said compressor and allows each refrigerant to flow into each of the outdoor heat exchangers connected in parallel and a plurality of second channel switching means, each performing switching such that either the refrigerant having passed through the bypass pipeline or the refrigerant from said indoor units is made to flow into each of said outdoor heat exchangers are provided in said outdoor unit;
• a pressure detecting sensor that detects pressure on a suction side of the compressor;
• and
• a controller configured to sequentially control switching of each second channel switching means during a heating operation when it is detected that the pressure on the suction side of the compressor is lower than a predetermined pressure to allow the refrigerant having passed through said bypass pipeline without having passed through an indoor unit of the plurality of indoor units to flow into at least one outdoor heat exchanger of the plurality of outdoor heat exchangers so as to defrost the at least one outdoor heat exchanger and to simultaneously allow the refrigerant having passed through said indoor units without having passed through the bypass pipeline to flow into at least one other outdoor heat exchanger of the plurality of outdoor heat exchangers and then after a predetermined time has elapsed to allow the refrigerant having passed through said bypass pipeline without having passed through an indoor unit of the plurality of indoor units to flow into at least one other outdoor heat exchanger of the plurality of outdoor heat exchangers and to simultaneously allow the refrigerant having passed through said indoor units without having passed through the bypass pipeline to flow into the at least one outdoor heat exchanger.