Display shows E9 and the compressor may not start or may run erratically.

Critical safety warning: Compressor and inverter circuits operate at high voltage. If you are not experienced with electrical diagnostics, contact a professional. Always unplug the refrigerator before any inspection.

Steps:

• Check for basic operation: Listen for compressor start attempts or clicking. Confirm condenser fan operation when the unit calls for cooling.
• Inspect wiring: At the rear, remove the lower cover and inspect the harness between the main PCB and the inverter module (if present) on the compressor. Look for loose plugs or burnt connectors.
• Check for overheating: Carefully feel (with power off) if the compressor shell is extremely hot, which may indicate a locked rotor or overcurrent condition.
• Test supply voltage (advanced): With appropriate tools and training, verify that the inverter is receiving correct AC supply and control signals. This is typically a technician-level task.
• Replace faulty module: If the inverter board shows visible damage or tests bad, replace it with the correct Sharp inverter module. If compressor windings are open or shorted, the compressor must be replaced, which generally requires a licensed refrigeration technician.

Due to the complexity and refrigerant system involvement, E9 faults are usually best handled by a qualified service technician.