Thermostat shows room temperature that is clearly too high or too low

Safety first: Turn off power to the HVAC system if you will remove the thermostat from the wall.

Steps to troubleshoot:

• 1. Compare with reference: Place a reliable thermometer near the thermostat and compare readings after 15–20 minutes.
• 2. Adjust calibration: In the thermostat settings, adjust the temperature offset to align with the reference thermometer within the allowed range.
• 3. Check location: Ensure the thermostat is not in direct sunlight, near appliances, or in drafts from doors, windows, or vents.
• 4. Clean vents: Use dry compressed air to gently clear dust from the thermostat’s vents.
• 5. Relocate if necessary: If the location cannot be improved, consider relocating the thermostat to a more representative area of the home.

When to call a professional: If the reading remains far off even after calibration, the internal sensor may be failing and the thermostat should be replaced by a technician.