An air-conditioning system (1) for an environment, in particular for the passenger compartment of a vehicle, is provided with an evaporator (13) and a compressor (18) coupled to the evaporator (13). In a system (30) for controlling the air-conditioning system (1), a control electronics (33) switches an operating condition of the compressor (18) when the temperature of the air leaving the evaporator (13) has a pre-set relation with a threshold temperature (Tthresh). The control electronics varies the value of the threshold temperature (Tthresh) as a function, in at least certain operating conditions, of a set-point temperature (Tsp), required by a user of the air-conditioning system (1), so as to reduce the energy consumption associated to the air-conditioning system.