Display shows COL or COOL; spa runs pumps but does not heat; temperature reading is very low

Safety: Ensure the spa is powered and protected from freezing conditions. Do not drain the spa in freezing weather.

• Verify actual temperature: Use a thermometer to confirm water temperature. If it is very low, allow the spa to run; the system is protecting itself.
• Check cover and insulation: Make sure the Bullfrog spa cover is closed and sealing properly to retain heat. Replace damaged cover gaskets or foam cores.
• Confirm pumps are running: During COL/COOL, the circulation pump and sometimes jet pumps may run to prevent freezing. Verify water movement at the jets and heater return.
• Allow time to heat: After a cold refill, it can take many hours to reach set temperature. COL/COOL should clear automatically as water warms.
• Sensor check: If COL appears when water is actually warm, test the temperature sensors as described in SN1/SN2 procedures and replace if out of range.

If COL persists with warm water and good sensor readings, the control pack may be misinterpreting sensor data; contact a Bullfrog dealer.