An automotive air conditioning system (1) comprising: ¢ an air cooling circuit (4) including a compressor (7), a condenser (8), an expansion valve (9) and an evaporator (10), fluidically connected to be flowed, during operation, by a heat transfer fluid, and a blower fan (15) associated with the evaporator (10) and operable to generate an airflow through the evaporator (10); ¢ an air heating circuit (5) including a liquid/air heater (16) configured to be flowed, during operation, by a heat transfer fluid and arranged close to the evaporator (10) to be flowed also by the airflow generated by the blower fan (15) associated with the evaporator (10), and a flow rate regulation solenoid valve (17) arranged to regulate the flow rate of the heat transfer fluid through the heater (16); and ¢ an electronic control unit (27) configured to receive a measured evaporator air temperature (T EVAP ) and a set cabin air temperature (T CSP ) and to switch an operating condition of the compressor (7) when the measured evaporator air temperature (T EVAP ) exhibits a given relation with at least one on/off threshold temperature (T T ) computed, in at least certain operating conditions, based on the set cabin air temperature (T CSP ).
