Display shows HL or HLo and spa shuts down or disables heater.

Safety first: Turn off power at the GFCI breaker before inspecting plumbing or equipment.

• 1. Confirm water level: Ensure the spa is filled to the recommended level on the skimmer. Top off if needed.
• 2. Open all valves: Verify that all slice valves around the pump and heater are fully pulled up (open). A partially closed valve can cause heater overheat.
• 3. Clean filters: Remove PDC Spas filters and rinse thoroughly. If they are old or collapsed, replace them. Test the spa briefly with filters removed to see if HL clears.
• 4. Check for air lock: If the spa was recently refilled, loosen the union on the circulation pump or main pump until air and water escape, then retighten. This helps restore full flow.
• 5. Observe flow: With power restored, verify strong water movement from the heater return and jets when the pump runs. Weak or no flow suggests a failing pump or blockage.
• 6. Reset the system: After correcting flow issues, turn power OFF for 1–2 minutes, then ON to clear the HL code. Monitor the spa for several heating cycles.

Call a technician if: HL returns quickly despite good flow and clean filters. The hi-limit sensor or control board may be faulty and require professional testing.