Display shows COL or COOL, heater is disabled and pumps may run to circulate water.

Safety: Ensure the spa remains powered during freezing conditions to allow freeze protection to operate.

• Verify actual water temperature: Use a separate thermometer to confirm the water is indeed cold. If the reading is normal but the spa shows COL, the sensor may be faulty.
• Allow spa to warm gradually: After a refill with cold water, COL may display until the system confirms stable readings. Keep the cover on to retain heat.
• Inspect temperature sensor: If COL appears in normal conditions, check the temp sensor connection at the control board and replace the sensor if readings are inaccurate.