Control panel shows HL or HILI and spa stops heating; pumps may still run but heater is disabled.

Safety: Turn off power at the GFCI breaker before touching wiring or heater components.

• Step 1 – Confirm water flow: Remove the AquaRest filter cartridge and check for strong water movement from the heater return jets when the spa is in heat/filtration mode. Weak flow can cause the high-limit to trip.
• Step 2 – Inspect heater tube and unions: Open the equipment access panel and locate the stainless heater tube on the AquaRest control pack. Check for kinks, partially closed slice valves, or debris at the heater unions that could restrict flow.
• Step 3 – Check sensor wiring: Locate the high-limit sensor leads plugged into the control board. Ensure the connector is fully seated and free of corrosion or moisture. Dry any condensation and reseat the plug.
• Step 4 – Reset power: Turn the breaker off for 5 minutes, then back on. If HL clears and does not return under normal operation, it may have been a temporary flow issue.
• Step 5 – Replace sensor if recurring: If HL returns quickly and water flow is confirmed good, the high-limit sensor may be out of tolerance. Replace the high-limit sensor that is strapped or threaded into the heater tube, using a part compatible with your AquaRest control pack.

If HL persists after sensor replacement, the control board may be misreading the sensor and should be evaluated by a spa technician.