When using the superheat method to verify refrigerant charge, what should happen if you add refrigerant?

When using the superheat method to verify refrigerant charge, adding refrigerant should lead to an increase in both suction pressure and temperature. This occurs because introducing more refrigerant into the system increases the volume of refrigerant vapor in the evaporator, which raises the pressure within the suction line. As the pressure rises, it lowers the boiling point of the refrigerant, allowing it to absorb more heat, thus increasing the suction temperature as the refrigerant vaporizes more efficiently.

This is fundamental to the operation of a refrigeration system. Proper refrigerant charge ensures that the system can effectively transfer heat. If the superheat is too low, it indicates that the system is undercharged or not operating efficiently, while a proper charge will yield an observable increase in both suction pressure and temperature when refrigerant is added. Understanding this relationship is critical for diagnosing and maintaining the efficiency of refrigeration systems.