Display shows Sn1 or SN, spa may not heat or may shut down heating cycle.

Safety: Turn off power at the GFCI before accessing the control pack or heater.

• Power reset: Leave power off for 2–3 minutes, then restore. If Sn1 returns immediately, the sensor circuit is likely faulty.
• Inspect sensor wiring: Open the equipment bay and locate the temperature sensor leads entering the control pack. Check for obvious damage, rodent chewing, or loose connectors. Reseat the plug firmly.
• Check sensor location: On many Beachcomber models, the sensor is threaded into the heater tube or mounted in a dry well. Ensure it is fully seated and not partially backed out.
• Compare temperature: Use a separate thermometer to compare actual water temperature with the displayed value. Large discrepancies indicate sensor failure.

Most Sn1 faults require replacement of the temperature sensor with a Beachcomber-compatible thermistor. This involves draining below the heater level on some models and should be done carefully to avoid leaks.