How to Fix / Troubleshooting

Safety first: Unplug the freezer. Allow any ice-covered components to thaw before handling to avoid breakage.

Steps:

Access the evaporator area by removing the inner rear panel.
Locate the defrost thermostat (a small round or oval device clipped to the evaporator tubing) and/or defrost sensor.
Check for obvious damage, such as cracked casing or burnt connectors.
With a multimeter, test the defrost thermostat for continuity when it is cold (below freezing). It should show continuity; if open, replace it.
Inspect and reseat the connectors going back to the main control board.
If the thermostat and sensor test good, the main control board may not be initiating defrost and may require replacement.

E4 displayed and freezer shows signs of heavy frost build-up or warm temperature

Possible Causes