To provide an air conditioning system and its control method for eliminating an unchanged range where a set temperature is not changed with the operation of an analog operation element even in a different operation mode or model, and to provide a temperature setting device and its control method.

The air conditioning system 1 comprises an operating device 30 having a temperature control dial 32, wherein a set temperature in an indoor unit 20 is set with the operation of the temperature control dial 32. The operating device 30 can output an instruction value continuously variable with the operation of the temperature control dial 32. In accordance with at least one of the operation mode of the indoor unit 20 and the model of the indoor unit 20, the variable range of the set temperature can be changed corresponding to the variable range of the instruction value continuously variable with the operation of the temperature control dial 32.