Er3
Fafco
Temperature Sensor Short Circuit
Controller displays Er3; temperatures shown are unrealistic and system may behave erratically.
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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
Shorted pool or roof sensor leads, Water intrusion into sensor junction box, Crushed sensor cable, Miswired sensor terminals
How to Fix / Troubleshooting
Safety: Disconnect power to the controller before testing wiring.
- Identify sensor: Consult the Fafco manual to determine whether Er3 refers to the pool or roof sensor.
- Inspect for shorts: Look for pinched cable under clamps, water-filled junction boxes, or bare conductors touching.
- Measure resistance: Disconnect the suspect sensor and measure resistance. A near-zero reading indicates a shorted sensor.
- Correct wiring: Ensure the sensor leads are not crossed or touching other terminals inside the controller.
- Replace sensor or cable: If the sensor itself is shorted, install a new Fafco-compatible sensor and reroute the cable to avoid damage.
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Repair Difficulty
Medium
3/5
Required Part
Fafco Temperature Sensor Harness
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