If your ambient temperature sensor is not reading accurately, you can calibrate it using the following steps:
1. First, make sure that the sensor is placed in a location where it will not be affected by direct sunlight or other sources of heat.
2. Next, find the current temperature using another reliable source, such as an outdoor thermometer.
3. Once you have the current temperature, adjust the sensor until it matches that reading. Make sure to write down the new setting so that you can remember it later.
4. Finally, check the accuracy of the sensor periodically to make sure that it has not drifted out of calibration.