A multi-split AC has one outdoor compressor, connected to four to five indoor air outlets via refrigerant lines rather than a complex duct system. Apart from the refrigerant tubing, the indoor air outlets are connected to the outdoor unit with condensate drain lines and power cables.

Although each indoor air outlets can be separately controlled, they are connected with the same outdoor heat pump unit to absorb or disperse heat. A heat pump works by removing the heat from the outdoor environment and transferring it indoors.