Thick ice sheet forming on the evaporator cover or behind the rear interior panel.

Safety warning: Unplug the freezer before accessing the evaporator and electrical components.

Steps to address defrost failure:

• Manual defrost first: Unplug the unit and allow all ice to melt completely. This may take several hours. Use towels to absorb water.
• Access evaporator: Remove the interior rear panel to expose the evaporator coil and defrost components.
• Test defrost heater: Disconnect heater leads and measure resistance with a multimeter. An open circuit indicates a failed heater that must be replaced.
• Check defrost sensor/thermostat: Test for continuity when the coil is cold. An open reading may indicate a failed sensor or thermostat.
• Inspect wiring and connectors: Look for burnt or loose connections in the defrost circuit.
• Replace failed parts: Install Summit-compatible defrost heater and/or sensor/thermostat as needed. Ensure proper mounting and contact with the evaporator.
• Reassemble and monitor: Restore power and observe operation over several days to confirm frost does not reaccumulate.