FS
Jandy
Flame Sense Fault
Display shows FS; heater will not fire or shuts down quickly.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Dirty or corroded flame sensor, Poor burner flame, Grounding issues, Faulty ignition control board
How to Fix / Troubleshooting
Safety first: Shut off power and gas before servicing. Allow heater to cool.
- Clean flame sensor: Locate the flame sensor rod near the burner. Remove it and gently clean the metal rod with fine steel wool or emery cloth to remove oxidation. Do not sand the ceramic.
- Check burner flame: After reassembly, observe the flame through the sight glass. It should be blue and stable. Yellow or lifting flames indicate combustion or gas pressure issues.
- Inspect ground connections: Ensure the heater chassis is properly grounded and that the flame sensor wire and ground wires are tight and free of corrosion.
- If FS persists: The ignition control board or gas valve may not be maintaining flame. A technician should measure microamp flame signal and replace the faulty component.
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Repair Difficulty
Hard
4/5
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