5 Possible Reasons Why Your Thermostat Stopped Working

A thermostat is an essential device for controlling the temperature in a home or office. It is usually connected to a heating or cooling system and can help to manage the temperature in a space. However, if a thermostat is not working properly, it can cause a great deal of discomfort and inconvenience.

Taking the time to troubleshoot and diagnose the issue can help to keep the thermostat working properly and prevent future issues. Here are some possible causes of thermostat malfunction.

1) Dust and Grime Buildup

Dust and grime buildup is one of the most common reasons why a thermostat stops working. Over time, dirt and dust can accumulate on the thermostat, which can cause it to malfunction. 

This buildup can also block airways and affect the thermostat’s sensors, preventing it from accurately reading the temperature. You can clean your thermostat using a damp cloth or vacuum cleaner attachment to prevent this issue from occurring.

2) Age of the Unit

The age of the unit is one of the most common factors for the effectivity of a thermostat unit. Older HVAC systems may not be compatible with newer thermostats and vice versa. 

If your thermostat is outdated, it may be time to upgrade to a newer model that is designed to work with your current HVAC system. Replacing the thermostat may be necessary to get it working again.

3) Wrong Mode Applied

If your thermostat isn’t working, you might need to check whether you have the right mode applied to the unit.

There is a chance that you might have inadvertently changed the mode from Heat to Cool or vice versa. To ensure that the thermostat is set to the correct mode, you should check the user manual for further instructions. 

Additionally, if the thermostat is not responding to the mode change, you should check the wiring and connections to ensure that everything is properly connected.

4) Thermostat Wi-Fi Not Connected

A Wi-Fi thermostat not connected could be one of the reasons why your thermostat stopped working. This could be the result of a weak or lost connection between the thermostat and your home’s Wi-Fi network.

You should also make sure that your home’s Wi-Fi signal is strong enough to reach the thermostat. If the connection is weak, you may need to move the thermostat closer to your router to ensure a strong connection.

5) Wiring Issues

Wiring issues can be one of the main reasons why your thermostat stopped working. If the wiring is done incorrectly, it can cause the thermostat to not get the power it needs to function properly. It is important to check the wiring to make sure it is connected correctly and that any loose connections are tightened.

Check for any corroded or damaged wires that may need to be replaced. If you are unsure of how to do this, it is best to contact a professional from Legacy Heating & Cooling to inspect and repair the wiring of your thermostat.


If your thermostat stops working, there are several potential causes that you should investigate. If none of these steps resolves the issue, it may be time to call a professional to take a look at your thermostat.

Legacy Heating can help you address any thermostat issues you need to fix. We are an HVAC contractor in Calgary and Edmonton that can identify the problem and repair it effectively. Get in touch with us today to learn how.

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