A computer-implemented method of controlling an operational mode of an outdoor unit connected to a plurality of indoor units, the method including: determining an operational mode of an outdoor unit; determining, at a master decision unit, a target outdoor mode for the outdoor air-conditioning unit based on the priority, the current area mode, the current area temperature, and the set point for each of the indoor units, the maximum actual standby duration and the maximum allowable standby duration of each of the indoor units, and the minimum active duration and the current active duration for the outdoor unit; and systematically controlling the operational mode to become the target outdoor mode when the target outdoor mode is different from the operational mode.