Plain-language explanation: This page is educational and does not replace testing the actual equipment.
Why technicians measure it
Superheat helps evaluate evaporator feeding and helps protect the compressor from liquid refrigerant return.
High superheat
High superheat may be associated with low refrigerant, a restriction, low evaporator feeding, or excessive heat load.
Low superheat
Low superheat may indicate overfeeding, low airflow, or conditions that could allow liquid refrigerant toward the compressor.
Why one number is not enough
Superheat must be interpreted with subcooling, airflow, indoor and outdoor conditions, equipment type, and manufacturer procedures.
Frequently asked questions
Is there one correct superheat number?
No. Target values depend on system design and operating conditions.
Can low airflow change superheat?
Yes. Airflow has a major effect on evaporator load and refrigerant behavior.
Is superheat only used on AC systems?
No. It is used in air conditioning, heat pumps, and refrigeration.