SN
QCA Spas
Temperature Sensor Fault
Display shows SN, SN1, or SN2, spa may not heat and may shut down heater circuit.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Open or shorted temperature sensor, Corroded sensor connector on control board, Damaged sensor cable, Sensor out of calibration
How to Fix / Troubleshooting
Safety: Turn off power at the GFCI breaker before accessing the control pack.
- Locate sensors: Open the equipment bay and find the temperature sensor on the heater tube or threaded into the plumbing near the heater on your QCA Spas pack.
- Inspect wiring: Follow the sensor cable to the control board. Check for cuts, rodent damage, or pinched wires. Reseat the plug on the board to ensure a solid connection.
- Compare water vs. displayed temp: With power restored, use a separate thermometer in the spa water. If the displayed temperature is far off (more than 5–10°F), the sensor is likely faulty.
- Replace sensor: With power OFF, unscrew or unclamp the sensor from the heater tube, quickly swap in a new QCA-compatible temperature sensor, and tighten. Avoid overtightening to prevent leaks. Restore power and verify the error clears.
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Repair Difficulty
Medium
3/5
Required Part
Temperature Sensor
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