There is described an air conditioning system with a refrigerant circuit, wherein the air conditioning system includes a leakage detection system. The leakage detection system comprises a room temperature sensor, an inlet temperature sensor for detection of a refrigerant temperature at a refrigerant inlet of a refrigerant evaporator, and an outlet temperature sensor for detection of a refrigerant temperature at a refrigerant outlet of the refrigerant evaporator. The sensors (34, 36, 40) are coupled with a calculating unit. In addition, there is described a method for leakage detection, in which a room temperature of the room to be air-conditioned is detected before the refrigerant evaporator on an air inlet side, a refrigerant inlet temperature is detected at the refrigerant inlet of a refrigerant evaporator, and a refrigerant outlet temperature is detected at a refrigerant outlet of the refrigerant evaporator.