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Lennox · Air conditioner

E180 Outdoor temperature sensor problem

Medium severity

What the control is telling you

No good reading from the outdoor sensor (the one in the outdoor unit, or the optional one on the indoor unit). S30/S40 alert code 180; unit control shows E180.

Applies to: Lennox communicating air conditioners incl. variable-capacity inverter units in S30/S40 smart thermostat systems

Likely causes

  • Open or shorted sensor or wiring
  • Sensor out of range

Test and repair steps

  1. Compare sensor resistance with the temperature/resistance chart in the unit installation instructions.
  2. Replace the sensor pack or stand-alone outdoor sensor.
  3. Sensors are detected at configuration and shown as installed in the About screen; reconfigure if a sensor was removed.
  4. Clears on configuration or when normal readings return.

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Source: Lennox Residential Communicating Systems Alert Code Guide (V2) 100017 (3/2023), Table 2 Alert Codes and Troubleshooting, p.18. Summarized in our own words; check the original manual for your model.

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