Service technicians often wonder how the refrigerated space temperature of a refrigeration system can be so high when the evaporator temperature is so cold. What the service technician fails to realize is that it is how active or full the evaporator is with vaporizing (phase changing) refrigerant that determines the cooling content or efficiency in any refrigeration system. An evaporator can be very cold but inactive with a lot of superheat, robbing it of its heat absorbing abilities.