A method of controlling an air conditioner system, the method including transmitting, by a first unit among a plurality of units belonging to a particular group, a wireless tuning command to a second unit; measuring, by the second unit, reception sensitivity and a transmission and reception success rate by wirelessly communicating with units belonging to the particular group while reducing a signal strength from a default signal strength; when the reception sensitivity and the transmission and reception success rate satisfy the predetermined standard, determining, by the second unit, that the signal strength corresponding to a level right before a level satisfying a predetermined standard is the signal strength to be used; and transmitting, by the second unit, information related to the determined signal strength to the first unit. Accordingly, an optimal signal strength at which mutual interference is prevented may be set.