F4 error, ice maker may not start compressor or may shut down unexpectedly

Safety: Unplug the unit. Compressor terminals carry mains voltage; only work on them with power disconnected.

Steps to resolve F4:

• Access compressor compartment: Remove the rear lower panel to expose the compressor and start components.
• Inspect start relay/PTC: Remove the plastic cover on the compressor terminals. Check the start relay/PTC for burn marks, rattling pieces, or melted plastic.
• Test relay/PTC: Use a multimeter to check continuity according to the part specifications. If it is open or physically damaged, replace it.
• Check wiring: Ensure all wires to the compressor and relay are firmly connected and not burned.
• Control board relay: If the start device is good but the compressor never receives power, the compressor relay on the main control board may be defective. Replace the control board.
• Technician note: If a new start device does not allow the compressor to start and the compressor windings test out of spec, the compressor itself may be failed and requires professional replacement.