E3
American Standard
Outdoor Temperature Sensor Fault
Thermostat displays E3 and outdoor temperature reading is missing or incorrect
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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 temperature sensor, Open or shorted sensor wiring, Incorrect polarity or miswired sensor at ODT terminals, Damage from weather or UV exposure
How to Fix / Troubleshooting
Safety: Turn off power to the outdoor unit and indoor unit at the breakers before working on sensor wiring.
- Verify sensor installation: Confirm that an American Standard outdoor temperature sensor is actually installed and wired to the ODT or S1/S2 terminals on the thermostat or communicating control.
- Check wiring connections: Inspect the sensor connections at both the thermostat and the outdoor sensor. Tighten loose screws and ensure no bare wires are touching each other or metal surfaces.
- Measure sensor resistance: Disconnect the sensor leads and measure resistance with a multimeter. Compare to the manufacturer’s temperature/resistance chart. If the reading is open, shorted, or far off expected value, the sensor is defective.
- Inspect sensor placement: The sensor should be mounted on a shaded exterior wall, away from direct sunlight, dryer vents, or exhausts. Relocate if necessary.
Resolution: Replace the outdoor temperature sensor if it fails resistance tests or is physically damaged.
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Repair Difficulty
Medium
3/5
Required Part
American Standard outdoor temperature sensor
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