A sequence of five frozen food cases operated by one compressor results in all five cases iced up. What is the likely problem?

• A. Low refrigerant charge
• B. Blocked condenser
• C. Too much oil
• D. Overheated compressor

Answer: (A)

Ice on all evaporator coils usually means the evaporators are running colder than they should, freezing moisture from the air. When a single compressor serves multiple display cases, a low refrigerant charge is the most likely cause because it reduces the amount of refrigerant circulating through the system. With less refrigerant, the evaporators can run with insufficient heat absorption and a lot of liquid refrigerant entering the evaporator, which pulls the temperature down toward freezing. The moisture in the room then freezes on the coil surfaces, frosting all five cases that rely on that compressor.

A blocked condenser would push up head pressure and reduce overall cooling, often leading to warm or inconsistent results rather than uniform icing. Too much oil can impair heat transfer but doesn’t typically cause widespread icing across all cases. An overheated compressor reduces cooling capacity but isn’t the typical trigger for frost buildup on every evaporator coil in a multi-evaporator setup.