Display shows HL or HLo, spa shuts down heater and sometimes pumps, water may feel very hot near heater outlet.

Safety first: Turn off power at the GFCI breaker. Do not use the spa until the cause of overheating is corrected.

• 1. Let the spa cool: Remove the cover and allow the water to cool below 100°F (38°C). This may take several hours.
• 2. Check filters and flow: Remove and clean the Coleman filter cartridge. Verify strong water movement from the circulation return and jets. Weak flow can cause localized overheating at the heater.
• 3. Bleed air from heater: Loosen the unions on the heater manifold slightly to release trapped air, then retighten once water appears. Air pockets can cause the high-limit sensor to trip.
• 4. Inspect the circulation pump: With power restored, confirm that the circulation pump runs during heating. If it is hot to the touch, noisy, or not moving water, it may be failing and should be replaced.
• 5. Check high-limit sensor connection: Locate the high-limit sensor (often a thermistor or manual reset switch on the heater tube). Ensure it is firmly attached and the wiring is intact. Some Coleman packs have a red reset button on the heater—press it once firmly with power off.
• 6. If HL persists: The high-limit sensor or heater assembly may be defective. Replace the high-limit sensor first; if the issue continues, have a technician test heater current draw and inspect for scale buildup inside the heater.