Display shows FLO or FL, heater will not turn on, jets may run briefly then stop.

Safety first: Turn off power at the GFCI breaker before opening any panels or touching internal components. Never run the spa with blocked suction or without water.

• 1. Check water level: Ensure the water level is above all skimmer openings and at least halfway up the filter housing. Low water can trigger FLO.
• 2. Clean or remove the filter: Unscrew and remove the Coleman filter cartridge. Rinse thoroughly with a garden hose from top to bottom. For testing, run the spa briefly without the filter (basket in place) to see if FLO clears. If it does, replace the filter.
• 3. Bleed air from the system: After a refill, loosen the union fitting on the circulation pump or heater inlet slightly to let trapped air escape until water seeps out, then retighten. Some Coleman models have a bleed screw on the pump face—open it carefully until air stops.
• 4. Inspect the pressure/flow switch: Locate the pressure/flow switch on the heater manifold. Check that both wires are firmly connected and that there are no kinks in nearby hoses. With power off, gently tap the switch body to free a stuck diaphragm. If FLO persists with good flow, the switch may need replacement.
• 5. Check circulation pump operation: With the cabinet open and power restored, verify that the small circulation pump runs continuously (or during heating cycles). If it hums but does not move water, it may be seized or air-locked. Turn power off and spin the pump shaft (if accessible) with a screwdriver to free it, or replace the pump if it will not start.
• 6. If unresolved: Do not bypass the flow switch. Contact a spa technician to test the pressure switch and circulation pump amperage and to verify heater manifold flow.