Display shows E3 and the refrigerator may not defrost; frost accumulates on the evaporator and rear wall.

Safety warning: Always disconnect power before accessing the evaporator or heater. The defrost heater operates at mains voltage.

Steps:

• Access the evaporator: Remove freezer drawers/shelves and the rear interior panel to expose the evaporator coil and defrost heater.
• Inspect visually: Look for burnt spots on the heater, melted insulation, or a tripped/bulged thermal fuse or bimetal thermostat attached to the coil.
• Test the heater: Disconnect the heater leads and measure resistance. A typical heater will show a finite resistance (e.g., 50–300 Ω depending on model). An open circuit (OL) indicates a failed heater.
• Test the thermal fuse/bimetal: With the coil cold (below freezing), the defrost thermostat should read near 0 Ω (closed). If it remains open, it is faulty.
• Replace faulty components: Install a Sharp-compatible defrost heater and/or defrost thermostat/thermal fuse as needed. Ensure all connections are tight and insulated.
• Check wiring and PCB: Inspect the harness from the heater assembly to the main PCB for burns or breaks. Verify the defrost connector is fully seated on the control board.

If E3 persists with a good heater circuit, the main control board’s defrost relay or triac may be defective and should be replaced by a professional.