Display shows FL2 and the heater is disabled; spa may run pumps but will not heat.

Safety: Shut off power at the breaker before working in the equipment bay.

• Power cycle: Turn the spa OFF at the GFCI for 2–3 minutes, then back ON to see if the code clears. Sometimes a transient glitch can latch FL2.
• Inspect flow switch wiring: Locate the flow switch on the heater manifold and trace its cable to the control pack. Look for pinched, cut, or melted insulation. Reseat the connector on the control board.
• Check for stuck switch: With power OFF, remove the flow switch from the plumbing if accessible. Inspect the internal paddle or plunger for scale or debris. Clean gently with a soft brush and reinstall with new Teflon tape if threaded.
• Continuity test: Disconnect the switch leads and test with a multimeter. With no water flow (pump off), the switch should be open (no continuity). If it reads closed, the switch is defective and must be replaced.
• Control board check: If a known-good switch still reads as closed to the board, the input circuit on the Hydropool control pack may be faulty and will require professional diagnosis and likely board replacement.