Display shows ER dF, refrigerator may stop cooling or show heavy frost on evaporator coils.

Safety: Disconnect power before accessing the evaporator area.

This code indicates the defrost system is not clearing frost from the evaporator.

• Inspect evaporator frost pattern: Remove the rear interior panel of the freezer or fresh food compartment (depending on model) to view the evaporator. A solid block of ice indicates defrost failure.
• Check defrost heater: Visually inspect the heater element at the bottom or around the evaporator for breaks or burn marks. Testing with a multimeter for continuity is recommended.
• Check defrost thermostat/bi-metal: The thermostat clipped to the evaporator tubing should show continuity when cold (below freezing). If it is open when frosty, it is defective.
• Inspect thermistor: Verify the defrost sensor (thermistor) is firmly attached to the evaporator and wiring is intact.
• Manual defrost: As a temporary measure, fully defrost the evaporator by unplugging the unit and leaving doors open until all ice melts. Mop up water. This will restore cooling for a short time but does not fix the underlying issue.

Because defrost system diagnosis requires electrical testing, many homeowners choose professional service.