Display shows HL and spa stops heating; pumps may continue to run in protection mode.

Safety: Turn off power at the breaker before touching any heater or sensor wiring.

• Cool the spa: Open the cover and allow the water to cool. Do not attempt to reset repeatedly without addressing the cause.
• Clean filters and check valves: Remove and clean filters. Ensure all slice valves around the pump and heater are fully open and locked in place.
• Inspect heater unions: With power OFF, check heater unions for partial blockages, collapsed gaskets, or debris. Remove unions if necessary to inspect the heater tube for scale or obstructions.
• Check circulation pump performance: Restore power and observe the circulation pump. If flow is weak or intermittent, the pump may be failing and overheating the heater.
• Sensor wiring: Verify that the high-limit sensor plug is fully seated on the control board and that the cable is not damaged or pinched.
• Professional descaling or replacement: If scale buildup is suspected inside the heater, a technician may need to chemically descale or replace the Hydropool heater assembly.