FLC
USSPA
Flow Switch Stuck Closed
Display shows FLC (flow closed) even when pumps are off; heater may not operate correctly.
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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 flow switch paddle or reed, Shorted flow switch wiring, Incorrectly installed or bypassed flow switch, Control board misreading flow input
How to Fix / Troubleshooting
Safety first: Turn OFF power at the breaker before working on plumbing or wiring.
- Inspect flow switch:
- Locate the flow switch body in the plumbing near the heater.
- Check for signs of physical damage or incorrect installation orientation.
- Check wiring:
- Follow the flow switch wires to the control board and ensure they are not pinched or shorted together.
- Reseat the connector on the control board.
- Functional test (for technicians):
- With power OFF, disconnect the flow switch from the board.
- Power ON briefly; if FLC changes to FLO or another code, the switch is likely stuck closed.
- Replace flow switch:
- Drain water below the level of the switch if necessary.
- Remove and replace with a USSPA-approved flow switch, ensuring correct orientation and sealing with proper gaskets or tape.
- Control board check:
- If a new switch does not resolve FLC, the flow input circuit on the control board may be faulty and require board replacement.
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Repair Difficulty
Medium
3/5
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