If five frozen food cases iced up on a single compressor, what is the most likely fault?

• A. Low refrigerant charge
• B. Faulty motor
• C. High head pressure
• D. Dirty evaporator

Answer: (A)

Low refrigerant charge is the most likely fault because when the system doesn’t have enough refrigerant, the suction pressure drops and the evaporating temperature falls. The evaporator gets exceptionally cold, so moisture in the air condenses and freezes on the coil and in the display area, causing ice buildup across multiple cases fed by that same compressor. This frost formation is a classic sign of undercharged systems under load, since there isn’t enough refrigerant to carry heat away effectively.

A faulty motor would usually stop or severely limit the compressor’s operation, not produce uniform icing across all cases. High head pressure points to condenser-side issues and excessive condenser pressure, which wouldn’t directly cause widespread evaporator icing. A dirty evaporator reduces heat transfer and can contribute to frost, but the symptom described—five cases iced up on a single compressor—is most consistently explained by a low refrigerant charge causing the evaporator to run colder than intended.