Display shows HL and spa stops heating; pumps may continue to run for cooling.

Safety first: Turn off power at the GFCI breaker if water feels excessively hot. Avoid using the spa until the issue is corrected.

• Check water level and filters: Ensure water is at proper level. Remove and clean filter cartridges thoroughly. Try running the spa briefly with filters removed to see if HL clears.
• Bleed air from heater and pump: With power OFF, loosen unions on the heater tube and circulation pump until water flows steadily, then retighten.
• Verify circulation pump operation: Restore power and confirm that the small circulation pump runs continuously in heating mode. If it hums, is noisy, or does not run, it may need replacement.
• Monitor temperature: Use an external thermometer to verify actual water temperature. If HL trips at normal temperatures, the high-limit sensor may be faulty.

Persistent HL errors after restoring proper flow indicate a failing sensor or control pack and should be checked by a professional.