What is the difference between superheat and subcooling methods for refrigerant charge verification?

Superheat and subcooling are two common methods for refrigerant charge verification. The superheat method measures the difference between the refrigerant’s saturation temperature and its actual temperature at the outlet of the evaporator coil. The subcooling method measures the difference between the refrigerant’s saturation temperature and its actual temperature at the outlet of the condenser coil. While both methods can indicate refrigerant undercharge or overcharge, superheat is more sensitive to undercharge, and subcooling is more sensitive to overcharge. Understanding the principles and limitations of each method is essential for accurate charge verification.