Refrigerator shows E4 and there is heavy frost buildup on the freezer back wall or poor cooling.

Safety first: Unplug the refrigerator. Be cautious of sharp metal edges and glass heater elements.

Steps:

• Manual defrost (temporary fix): Remove food from the freezer, leave the door open, and place towels to catch water. Allow 12–24 hours for ice to melt. This will temporarily restore airflow but does not fix the underlying issue.
• Access defrost components: Remove freezer shelves and the rear interior panel to expose the evaporator coil. The defrost heater is typically a glass or metal tube at the bottom or woven through the coil. The defrost thermostat (bi-metal) is clipped to the coil.
• Check continuity: With a multimeter, test the defrost heater for continuity. A reading of infinite resistance indicates a failed heater. Test the defrost thermostat (only when cold/frosty); it should show continuity when cold.
• Inspect wiring: Look for burnt connectors or broken wires between the heater, thermostat, and harness.
• Replace failed parts: If the heater is open, replace it with a Magic Chef-compatible defrost heater assembly. If the thermostat is open when cold, replace it with the correct defrost thermostat. Reconnect all wiring securely.
• Reassemble and test: Reinstall the panel and shelves, restore power, and monitor for several days. Frost should no longer build up heavily on the back wall.

Note: If heater and thermostat test good, the main control board may not be initiating defrost and may require replacement.