What do high superheat and high subcooling suggest?

High superheat and high subcooling are indicative of a restriction in the refrigerant flow within the HVAC system. Superheat is the temperature of the refrigerant vapor above its saturation point, while subcooling refers to the temperature of the liquid refrigerant below its saturation point. When superheat levels are elevated, it suggests that the refrigerant is not adequately absorbing heat in the evaporator, typically due to insufficient refrigerant flow. Simultaneously, high subcooling indicates that there is excess liquid refrigerant condensing in the condenser, which can occur when a restriction prevents the refrigerant from flowing freely.

Thus, when both high superheat and high subcooling are observed, it signals that the refrigerant is having difficulty circulating through the system, commonly a symptom of a blockage or restriction, such as a clogged filter dryer, a bent line, or an expansion device malfunction. This situation highlights the importance of maintaining proper refrigerant charge and flow within HVAC systems to ensure efficient operation.