What does high superheat and low subcooling indicate?

High superheat indicates that the refrigerant has absorbed a significant amount of heat before it changes from a liquid to a gas in the evaporator coil. This can suggest that the evaporator is not receiving enough refrigerant, leading to inadequate cooling. In this scenario, low subcooling suggests that the refrigerant is not being adequately cooled after it has condensed back into a liquid in the condenser.

When both high superheat and low subcooling are present simultaneously, it typically points to an undercharged refrigerant system. An undercharged system struggles to maintain the necessary refrigerant flow, which causes less heat to be absorbed in the evaporator, resulting in higher superheat levels. Meanwhile, not enough refrigerant is present in the system overall to ensure effective condensation, leading to low subcooling.

In summary, high superheat reflects a potential issue in the evaporator related to insufficient refrigerant for proper operation, and low subcooling indicates a similar issue in the condenser. Together, these symptoms predominantly indicate an undercharged refrigerant system.