A system or a method for performing capacitive sensing of humidity/liquid, primarily in conductive or non-conductive liquid/gas mixtures, having a control unit and at least first and second sensor electrodes, the capacitance between the first and the second electrodes being measured. To measure humidity/liquid in a circulating gas/liquid mixture at least one of the sensor electrodes is formed as a tube which is placed in the liquid/gas mixture. Based on the capacitance measurements, a calculation of at least one dataset for control of a second system is performed. The tube can be more or less filled up with liquid or gas and the capacitance can be measured as it depends on the content around or inside the tube, and if a dry gas is there will be one value of capacitance and in a situation where the gas is being replaced by liquid, the capacitance value will change rapidly.