Trane Open Outdoor Sensor Circuit

Thermostat displays outdoor temperature as -- or blank even though a sensor is installed

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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

Broken wire to Trane outdoor temperature sensor, Loose sensor terminal screws, Sensor not enabled in thermostat configuration, Failed outdoor sensor element

How to Fix / Troubleshooting

Safety: Turn off power to the HVAC system before working on sensor wiring.

  • Step 1 – Confirm sensor is enabled: In the thermostat installer setup, ensure the outdoor sensor option is turned ON.
  • Step 2 – Inspect sensor wiring: At the sensor location and at the thermostat/indoor board, tighten terminal screws and check for broken or corroded wires.
  • Step 3 – Test sensor resistance: Disconnect the sensor and measure resistance with a multimeter. Compare to Trane’s temperature/resistance chart. If open circuit, replace the sensor.
  • Step 4 – Replace sensor if needed: Install a new Trane outdoor temperature sensor and route wiring away from high-voltage lines.
  • Step 5 – Restore power and verify: After replacement, restore power and confirm that the thermostat now displays outdoor temperature.
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Repair Difficulty

Medium 3/5

Required Part

Trane Outdoor Temperature Sensor
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