FS
Jacuzzi Flow Switch / Flow Sensor Fault

Jacuzzi pool heater shows FS and may not maintain stable temperature.

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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

Stuck or fouled flow switch, Low water flow, Incorrect installation orientation, Damaged flow sensor wiring

How to Fix / Troubleshooting

Safety first: Turn off power and close isolation valves before removing any water-side components.

Steps to address FS:

  • Verify pump operation: Ensure the circulation pump is running and fully primed. Check for air in the system.
  • Clean filter and baskets: Restore proper flow by cleaning the pool filter and pump basket.
  • Inspect flow switch: Locate the Jacuzzi flow switch in the plumbing near the heater. Remove it and check for debris, scale, or a stuck paddle/magnet. Clean gently and reinstall in the correct flow direction.
  • Check wiring: Inspect the flow switch cable and connector for damage. Replace the switch if it does not change state with flow.
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Repair Difficulty

Medium 3/5

Required Part

Jacuzzi Flow Switch
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