To serve you better, we remain open 24/7 during the COVID-19 outbreak. Learn More

Signs That You Have a Broken Thermostat

Whether it’s the winter or the summer, your home’s thermostat keeps you comfortable at all times, so when you have a broken thermostat it can be devastating.

During a snowstorm in January and on the hottest day in July, you use your thermostat to create the ideal environment for your home. This wonderful device allows you to have complete control over the temperature in your home. But when this device isn’t working, your whole family may experience discomfort as you’re looking to find the best solution to keep them at ease. There are a number of clear signs that you have a broken thermostat.

The list below compiles the most common indications of a broken thermostat:

The thermostat won’t turn on

The most clear sign of a broken thermostat is that the device won’t turn on and is completely unresponsive. If your thermostat displays an empty black screen and won’t turn on, then it needs to be inspected to find out if there is a solution to the problem.

The room temperature and thermostat setting aren’t synchronized

It may seem as though your thermostat is working, but it’s as though your temperature setting changes are being lost in translation. When the room temperature and the thermostat setting aren’t coordinated with each other then it’s likely that there is a problem.

You can check the difference in temperature if you have a room thermometer at home. If not, then one can be purchased at any home hardware store. Compare the results of the room thermometer to your thermostat settings and see if there is a difference.

This problem could also be related to an incorrect placement of your home thermostat. If the thermostat is placed in direct sunlight or in an area which would affect it’s temperature in any way then it would be reading the temperature of your home incorrectly. If this is the case then your thermostat should be moved to a located that is better suited for accurate temperature readings.

The temperature isn’t changing

If you notice that your furnace or AC is running but is not responding to the temperature adjustments you’re making then there is most likely a problem. You can test whether or not your furnace or AC are responding to temperature changes by performing a simple test.

If it is winter then set the temperature 5 degrees warmer than it is currently set to. If it is summer then set it to be 5 degrees cooler than it currently set to. Now wait a couple minutes and see if you notice a change in the air coming from the vents. If you experience no change in the temperature of your home then there is a problem. This problem is either with the thermostat or it is with the furnace or AC. Contact a trusted HVAC professional to diagnose the issue and provide you with the ideal solution


Now that you know a few clear signs of a broken thermostat, let’s take a look at why this might happen.

You’ll also want to know if/how you can fix it, so we’ll assist you in that as well.

Your thermostat is not turning on

There are a number of reasons as to why your thermostat is not powering on:

  • The batteries are low. When the device is running low on battery it’s common to see it not perform properly or not turn on at all. If your thermostat is run on batteries and you’re experiencing this issue, try replacing the batteries.
  • The wiring is damaged or faulty. A problem related to wiring is more complicated than a battery issue. If your problem is likely related to the wiring then call an HVAC professional to take a look. Do not attempt to fix the wiring on your own as you may do more harm than good.
  • The breaker switch is set to off. This problem only affects wired thermostats. If you own a wired thermostat, go to where your breaker switches are located and flip the one labelled “thermostat” to the on setting. If it is already set to on then try switching it to off and then back to on again.

The thermostat anticipator is in need of an adjustment

If you have an old non-digital thermostat then it most likely has an anticipator inside it. This anticipator could be set to the wrong setting and would need an adjustment.

Once you open up the thermostat you will find a metal tab. This metal tab is the anticipator you’re looking for. The anticipator has labels which indicate which setting is for the longer and shorter cycle. Adjusting this setting will allow you to manually change how long your AC or furnace will cycle for.

This is typically a temporary fix for a bigger problem. Problems relating to your furnace or AC never turning off or short-cycling are related to an incorrect sizing of the AC or furnace unit. This could cause many problems along the way for the performance of your furnace or HVAC unit. Notify an HVAC professional about the issue and have it sorted to ensure that you don’t experience equipment failure in the future.

Dust buildup inside the thermostat

Dust and debris buildup will affect any mechanical device. Cleaning the dust buildup inside your thermostat is easy and could make your device work properly again. Before getting started, make sure that the device is set to off. Remove the cover off the thermostat and clean the interior with a cloth or brush to remove the excess buildup.

Your thermostat has reached the end of its lifecycle

The typical thermostat should last ten years. It is expected that these devices will experience issues or break past the 10 year mark. If this is the case for you then it is time to get a new thermostat.


If you have any further questions regarding your broken thermostat or any of your other HVAC needs, DeMark Home Ontario is here to solve those problems. Our experienced staff would be happy to assist you and be the solution to the HVAC issue you’re experiencing. Our trained and experienced technicians will provide you with quick and efficient HVAC service and replacement. Call us at 647-847-2998 or fill out our online request form and we will be happy to assist you with your request.

Easy Rentals...

get total piece of mind with our High Efficiency Furnace and Air Conditioner Rental Program.


Customer Rating of 5.0
based on Google reviews

  • Get A Quote Today! Free in-home estimate!
  • This field is for validation purposes and should be left unchanged.

Upgrading to a high-efficiency heating and cooling system offers more than energy savings.

Take advantage of these rebates today!


This item comes with absolutely free standard installation. We’ll ensure that the product is completely installed to code and fully functioning prior to leaving.


Great news! Receive a brand new digital thermostat absolutely free when renting this HVAC product from DeMark Home Ontario.


Great news! When renting a furnace or air conditioner, you’ll get your first 2 months absolutely rent free.


Great news! When renting a furnace and air conditioner together, you’ll get your first 3 months absolutely rent free.


This product carries a manufacturer warranty and we’re happy to explain it in full to you. Feel free to get in touch with us for more information or see the Warranty Information tab for more information


If your order is placed and confirmed by 11am, we can have your HVAC product installed within the same day.

Certain conditions apply, not available on all products.


This water heater is subject to reduced rental rates based on the DHO discount program. Save money on your bill every single month!

Some conditions apply


Save money on this item when buying it along with a qualifying high-efficiency furnace or air conditioner.

Some conditions apply


Great news! When renting a qualifying water heater, you’ll get your first 2 months absolutely rent free.


Promotional code can be found on the eFlyer, Brochure or promotional email that you received from us.

*If you are an existing customer please refer to the mail or email that was sent to you after the installation of your equipment as it contains your promotional code. If you are having troubles locating it please call us and one of our Customer Service Representatives will be happy to assist you.

  • Please fill out the form below in order to schedule service and be sure that your request will be processed promptly and you will hear back from us shortly.

Notice for Power Vent Water Heater Customers

Effective August 2007, gas code requires technicians working on venting to replace black ABS vent pipe with white UL-certified vent pipe.

We will upgrade your venting pipes at no additional cost.

  • Forum Registration

  • Forum Rules

    Registration to this forum is free!
    You must abide by the rules and policies detailed below. If you agree to the terms, please check the 'I agree' checkbox and press the 'Register' button below.

    Although the administrators and moderators of DeMark Home Ontario Forum will attempt to keep all objectionable messages off this forum, it is impossible for us to review all messages. All messages express the views of the author, and DeMark Home is not responsible for the content of any message.

    By agreeing to these rules, you warrant that you will not post any messages that are obscene, vulgar, sexually-oriented, hateful, threatening, or otherwise violative of any laws.

    The owners of DeMark Home Ontario Inc reserve the right to remove, edit, move or close any thread for any reason.



Send this to a friend