Display shows COOL and spa will not heat to set temperature immediately after refill or long standby

COOL is typically an informational message indicating the water is significantly below the set temperature.

• Verify water level and flow: Ensure the spa is properly filled and filters are clean.
• Allow time to heat: Close the cover and allow several hours for the heater to bring the water up to temperature. Large Artesian spas can take 12–24 hours to reach setpoint from cold.
• Check for actual heating: Confirm that the heater indicator is on and that the water temperature is slowly rising over time.

If COOL persists and the water does not warm, troubleshoot as a no-heat condition (heater, sensors, or control board).