Error code Er dH is displayed; the refrigerator may show signs of heavy frost on the evaporator and poor cooling.

Safety first: Disconnect power before accessing the evaporator area. Use insulated tools and avoid contact with sharp fins.

Steps:

• 1. Visual inspection: Remove the freezer or fresh food rear interior panel (depending on model) to expose the evaporator coil. Look for a solid block of ice covering the coil, which indicates a defrost failure.
• 2. Manual defrost: Unplug the unit. Place towels and a pan to catch water. Use a hair dryer on a low setting to melt ice from the coil and surrounding area. Do not use sharp tools to chip away the ice.
• 3. Locate defrost heater: The heater is typically a glass or metal tube located at the bottom of or woven through the evaporator. Inspect it for visible breaks or burn marks.
• 4. Test heater continuity: Disconnect the heater wires. Use a multimeter set to ohms to check for continuity. A reading of OL (Open Loop) indicates a failed heater that must be replaced.
• 5. Check defrost thermostat/bi-metal: The thermostat is clipped to the evaporator tubing. When it is cold (below freezing), it should show continuity. If it remains open when cold, it must be replaced.
• 6. Inspect defrost thermistor (if equipped): Some models use a thermistor instead of a bi-metal. Measure its resistance at known temperatures and compare to the service data. Out-of-range readings indicate that a replacement is needed.
• 7. If heater and sensors test good: If the heater and sensors test good, the main control board may not be initiating the defrost cycle. Inspect the board for burnt spots. Replacement of the control board is often required and is best handled by a technician.