Display shows COL or COOL, heater does not run, spa may run pumps to circulate water.

Safety first: Ensure GFCI protection is functioning before operating the spa.

• Verify water temperature: Use a separate thermometer to confirm the actual water temperature. If it is simply cold, allow the spa time to heat.
• Check cover and insulation: Make sure the Aquaterra spa cover is in good condition and properly latched to retain heat.
• Confirm set temperature: On the topside control, verify that the set temperature is higher than the current water temperature.
• Observe heating: The spa may display COL while it is in the process of heating from a low temperature. This is normal. If the temperature does not rise over several hours, there may be a heater or sensor issue.

If the spa never begins heating and remains in COL status, test the heater and temperature sensor or contact a technician.