Magic Chef freezer shows E3 and may not defrost properly, leading to frost buildup and warm temperatures.

Safety: Unplug the freezer before testing any components. The defrost heater operates at line voltage and can cause shock if mishandled.

Diagnostic steps:

• Inspect for heavy frost: Remove the interior rear panel. If the evaporator is encased in solid ice, the defrost system is not working.
• Locate defrost components: Identify the defrost heater (usually a glass or metal tube at the bottom or woven through the evaporator) and the defrost thermostat/thermistor clipped to the coil.
• Test the defrost thermostat (if present): With the coil still cold (below freezing), disconnect the thermostat and check continuity. It should read closed (0Ω–1Ω). If it is open when cold, it is defective.
• Test the defrost heater: Disconnect the heater leads and measure resistance. Typical values are 20–150Ω depending on the model. An open circuit (OL) means the heater is bad.
• Check wiring and connectors: Inspect the harness from the heater and thermostat to the control board for burns, breaks, or loose plugs.
• Replace failed parts: If the thermostat or heater tests bad, install the correct Magic Chef replacement part, matching the original mounting and routing.
• Force a defrost (if your model allows): Some Magic Chef electronic controls allow entering a service mode to energize the defrost heater. Only do this if you are comfortable and have the tech sheet; otherwise, leave this to a technician.
• Clear ice and reassemble: Fully defrost the evaporator, reinstall the cover, and restore power. Monitor for 24 hours to confirm normal frost pattern and that E3 does not return.

When to seek service: If the heater and thermostat are good, the main control board’s defrost circuit may be faulty and should be professionally evaluated.