Safety: Turn off power at the breaker before removing panels or touching wiring.

Clean filter thoroughly: Remove the filter cartridge and hose it off. If it is older than 1–2 years or has collapsed pleats, replace it with a Saratoga-compatible filter.
Test with filter removed: With the filter out and basket in place, restore power and see if FL clears. If it does, the filter is the restriction.
Bleed circulation pump: Locate the small circulation pump in the equipment bay. Loosen the discharge union slightly to release trapped air, then retighten. Restore power and check for normal flow at the heater return.
Inspect flow switch wiring: Confirm the two wires on the flow switch are firmly attached and not corroded. Gently wiggle the harness with power OFF and reseat connectors on the control board.
Check for kinked hoses or closed valves: Make sure all slice valves are fully open and no vinyl hoses are kinked or collapsed.

If FL remains, the circulation pump or flow switch may need replacement and the control system should be tested by a spa technician.

Display shows FL, spa may not heat, circulation pump may run continuously or cycle.

Possible Causes