Hot, superheated vapor enters at point A. From point A to B, the superheat is removed. The vapor is saturated at point B. Condensing then starts, and saturated vapor is converted into a liquid. At point C, the refrigerant is 100% saturated liquid. The third step, from point C to D, is to subcool the liquid refrigerant by reducing the temperature. In a well-designed system, this process is carried out with a minimal drop in pressure, (rarely more than 10 psi). EXCERPT FROM THE RAC SERIES FROM THE ONLINE STORE AT RSES .