Air conditioning system

An air conditioning system performing a refrigeration cycle in a refrigerant circuit including an outdoor unit, a plurality of indoor units, a refrigerant connection pipe connecting the outdoor unit and the indoor units, the air conditioning system comprising:

• an electric valve decompressing a refrigerant flowing in the refrigerant circuit in accordance with an opening degree;
• a detector for detecting a change of the number of operating units that are the indoor units under operation;
• and
• a controller for controlling a state of the electric valve,
• wherein the controller executes a first control when a change of the number of operating units is detected by the detector, and adjusts the opening degree of the electric valve in the first control to suppress a rise of pressure of the refrigerant flowing into an operating unit,
• when the change of the number of operating units is detected by the detector, the controller executes the first control on condition of the system being in a first state in which a total value of air conditioning capacities of the indoor units having been subject to change of an operating state is a predetermined reference value or more, and
• the reference value is a value at which an occurrence of variation in an operating capacity of the system is estimated at a level that causes an increase of noise in the operating unit.