Display shows “COOL”; spa is below set temperature and heater may be disabled temporarily.

Safety first: No immediate hazard, but ensure GFCI protection is working.

• Allow time to heat: After a refill, it can take many hours for the No-Fault heater to bring the spa to set temperature. Leave the cover on and minimize use.
• Verify circulation: Confirm the circulation pump is running as scheduled and that there is flow from the heater return.
• Check set temperature: Make sure the set point is higher than the current water temperature.
• Power-cycle if stuck: If COOL remains even after the spa is warm, power off for 30 seconds and back on. Persistent false COOL may indicate a sensor issue.