Method of determining the presence of incondensable gases in a climate station cylinder for recharging motor vehicle air conditioning systems. One of the pressure sensors will be used that is present in the charging station and designed for monitoring the operations in the A/C system of the vehicle, placed on the low pressure LP and/or high pressure HP lines of the climate station, so that in case of verification of the incondensable gases, the control electronics opens a coolant charging valve and an HP/LP separating valve, thereby flooding the service pipes so as to receive the pressure signal from one of the service pressure sensors, LP or HP, of the station, and compare the value with the temperature T of the cylinder and check whether such pair of values is a corresponding parameter, without tolerances, of a pressure-temperature curve of the pure coolant.