E3
Day & Night
Outdoor Coil Temperature Sensor Fault
E3 error, outdoor fan may stop, unit shuts down on hot days
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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
Failed outdoor coil thermistor, Loose or corroded thermistor connector at outdoor board, Damaged sensor wiring from UV or rodents, Faulty outdoor control board sensor circuit
How to Fix / Troubleshooting
Safety first: Turn OFF the outdoor disconnect and verify the fan has stopped before removing the service panel.
- Step 1 – Locate the sensor: On Day & Night condensers, the outdoor coil sensor is usually clipped to the condenser coil tubing or mounted near the coil inside the cabinet. Identify the small probe with two wires leading to the control board.
- Step 2 – Inspect and reseat: Check that the sensor is firmly attached to the coil and that its connector at the board is fully seated. Clean any corrosion from terminals.
- Step 3 – Check wiring: Look for cracked insulation, chewed wires, or pinch points where the cabinet may have cut the cable. Repair or replace damaged wiring.
- Step 4 – Test sensor: With power OFF, disconnect the thermistor and measure resistance. Compare to manufacturer temperature/resistance chart. Replace if open, shorted, or out of range.
- Step 5 – Restore power and test: After replacing or reseating the sensor, restore power and run the unit. If E3 persists, the outdoor control board may require replacement.
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Repair Difficulty
Medium
3/5
Required Part
Outdoor Coil Temperature Sensor (Condenser Thermistor)
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