Relay Failure — Sources and Solutions
Relays are electrically operated switches used throughout a refrigerator to control high-current components — most notably the compressor start relay, fan relays, and defrost relays. A relay failure means one of these switches is stuck open, stuck closed, or not responding to control signals.
What Triggers This Error?
The main PCB monitors whether components respond correctly when their relay switches them on or off. If a component fails to start when commanded — or fails to stop — the board infers a relay fault.
Common Sources
- Compressor start relay failure: The most common relay fault. The start relay helps the compressor motor overcome starting inertia. When it fails, the compressor clicks repeatedly but never starts.
- Contact welding: High current arcing can fuse relay contacts in the closed position, leaving a component permanently energized.
- Coil burnout: The relay’s electromagnetic coil burns out due to overvoltage or age, preventing it from switching at all.
- Mechanical wear: Relay contacts erode over thousands of switching cycles, eventually failing to make reliable contact.
Solutions
- Diagnose the start relay first: Remove the compressor start relay (it plugs into the side of the compressor). Shake it — a rattle means a broken internal component. Replace it.
- Test relay coil resistance: Use a multimeter to check coil resistance against the specification on the relay body. An open reading means the coil is burnt out.
- Test relay contacts: In the off state, contacts should show open circuit. A short reading across normally-open contacts means they are welded shut.
- Replace the faulty relay: Most relays are inexpensive, socketed components available from appliance parts suppliers.
- Replace the control board: If the relay is soldered onto the PCB and non-replaceable as a discrete component, a full board swap is required.