GE freezer shows E4 and may not defrost properly, leading to frost buildup

Safety warning: Disconnect power before working near the evaporator and defrost components. Use gloves to avoid cuts from sharp metal.

Steps to address E4:

• Defrost access area: Remove food and shelves. If the rear panel is heavily iced, allow the freezer to sit unplugged with the door open or use a hair dryer on low (kept away from water) to melt enough ice to remove the panel safely.
• Remove rear interior panel: Unscrew and remove the panel to expose the evaporator coil and defrost components.
• Locate the defrost thermistor: This sensor is usually clipped to the evaporator tubing or near the defrost heater. It may be separate from the main evaporator thermistor.
• Inspect placement and wiring: Ensure the sensor is firmly attached to the coil where it can accurately sense temperature. Check for broken wires, chafing, or connectors damaged by ice.
• Test the thermistor: Disconnect it from the harness and measure resistance with a multimeter. Compare to the temperature/resistance chart in the tech sheet. If readings are open, shorted, or far off spec, replace the sensor.
• Replace if needed: Install a new GE defrost thermistor, clipping it securely to the evaporator tubing in the original location. Route wires away from the heater and fan.
• Reassemble and test: Reinstall the panel, restore power, and allow the freezer to run through at least one defrost cycle. The E4 code should clear if the sensor is functioning.

Note: If the thermistor tests good and wiring is intact, the main control board may not be processing defrost sensor input correctly and may require replacement.