There could be several reasons why the s40 is displaying an ambient temperature that doesn't match the actual temperature in the home. 1. sensor error: the built-in temperature sensor or the external temperature sensor might be faulty. if the sensor reads -4°f or less or 158°f (+ 5°f) or greater, it will display an error. 2. sensor calibration: the indoor temperature displayed on the controller might differ from the actual indoor temperature. you can calibrate the sensor using the room temperature sensor calibration button under the service menu. 3. sensor location: if the temperature-sensing bulb is located in the control box or compressor compartment, the ambient temperature sensed may be 10 to 15°f higher than the outdoor ambient. this temperature variation may be due to several factors: compressor run time, crankcase heater run time, and direct sunlight on the control panel. 4. wi-fi connection: if the thermostat is set to get the outdoor temperature from accuweather, it needs to be connected to wi-fi. if it's not connected, it might not display the correct temperature. 5. registration: the s40 thermostat needs to be registered for online access with lennox. if it's not registered, it might not display the correct temperature. 6. temperature source: the outdoor temperature displayed in your thermostat's home screen can come either from the sensor in your outdoor unit or from accuweather. you can choose between these two sources under menu > display settings > home screen > outdoor temperature source. if the source is not set correctly, it might display the wrong temperature. if none of these solutions work, you might need to contact a service contractor to replace the thermostat or the external temperature sensor.
For more information or a visual representation of steps please reference our user guide here
