Air conditioning system and control method

The embodiment of the invention provides an air conditioning system and a control method, relates to the technical field of air conditioning equipment, solves the problem of unreasonable starting time for starting a sterilization mode and quitting time for quitting the sterilization mode in related technologies, and also relates to solving of the linkage problem of different sterilization modes and dehumidification modes. The air conditioning system comprises an outdoor unit comprising an outdoor heat exchanger, an indoor unit comprising an indoor heat exchanger and a controller. The controller is configured to start a sterilization working mode of the air conditioning system when the accumulated operation duration of the air conditioning system is larger than or equal to an operation duration threshold value, or when the time interval between the last starting time and the last starting time of the air conditioning system is larger than or equal to a time interval threshold value; according to the correspond