Is your thermostat showing the wrong temperature? All central heating, ventilation and cooling (HVAC) systems have a thermostat. It’s the primary interface with which you can control your HVAC system’s equipment.

The thermostat will display the current temperature. After setting it to the appropriate mode (heating vs cooling), you can set the desired temperature. Your HVAC system will then run until this temperature has been reached. If your thermostat is displaying the wrong temperature, though, your HVAC system will either make your home too hot or too cold.

Faulty Sensor

Your thermostat may show the wrong “current” temperature if the sensor is faulty. Thermostats work in conjunction with a temperature sensor. The temperature sensor will measure the temperature of the air, and the thermostat will display it. If the temperature sensor fails, the thermostat may display the wrong temperature.

Poor Sensor Placement

Even if the temperature sensor is functional, poor placement may result in your thermostat showing the wrong temperature. Some of the rooms and spaces in your home may have a different temperature than others. The temperature sensor, of course, will only measure the temperature of the immediate, surrounding air.

Some thermostats have a temperature sensor built into them. Therefore, installing the thermostat near a heat source like a sun-lit window may result in a higher-than-normal temperature. Other thermostats use a remote sensor. Regardless, if your thermostat is displaying the wrong temperature, you should check the sensor placement.

Unlevel Mercury-Based Thermostat

Older thermostats use mercury to measure the temperature of the surrounding air. If you have one of these mercury-based thermostats, you need to make sure it’s level. An unlevel mercury-based thermostat won’t be able to measure the correct temperature. If it’s titled or otherwise not level, it will display the wrong temperature, which will throw off your HVAC system’s performance.

Low Batteries

Another possible reason your thermostat is showing the wrong temperature is low batteries. Most thermostats use batteries. Some of them use batteries for all of their functions, whereas others only use batteries for backup and programming purposes.

Low batteries may cause issues with your thermostat. Your thermostat may show the wrong temperature, or it may not show any temperature. Fortunately, this is a quick fix. Just remove the cover on your thermostat, pull out the dead batteries and replace them with new batteries of the same type.