The reason subcooling would be below 8 degrees on an air conditioning system is due to which condition?

• A. Dirty or blocked condenser coil
• B. Overcharged refrigerant
• C. Low ambient temperature
• D. Undercharged evaporator

Answer: (A)

Subcooling is how far the liquid refrigerant leaving the condenser is cooled below the condenser’s saturation temperature. When the condenser coil is dirty or blocked, heat transfer from the refrigerant to the ambient air is impaired. This means the refrigerant can’t condense as effectively, so the condensing temperature rises. The liquid line doesn’t drop as far below that higher condensation temperature as it should, so the subcooling value falls, often below the 8-degree target. In short, restricted heat rejection due to a dirty condenser keeps the liquid hotter relative to its condensation temperature, reducing subcooling.