A new technology called RAD was developed to detect the amount of refrigerant in system air conditioners installed in different places. System air conditioners were first introduced to households in 2000 and can vary their cooling power from 2.0 kW to 186 kW. When they are set up in high, far-off locations, around 100 kg of refrigerant is usually used in the whole system. The RAD technology uses modern methods to control the refrigerant cycle and measure the system's refrigerant amount accurately.