Why Does My Thermostat Say Check System?

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Why Does My Thermostat Say Check System?

Modern HVAC thermostats are wonderful devices. Digital technology has made them “smart” and given them the ability to communicate with your furnace and/or air conditioner. Along with all the advantages come some complications. In the old days, a mechanical thermostat either worked or it didn’t; but in today’s Illinois and Northwest Indiana homes thermostats can sometimes give you confusing alerts and messages.

Common Message

A good example is the “check system” message that appears on your thermostat. In principle it’s much like the “check engine” light in your car. It means the monitoring system has spotted something out of the ordinary. It can be very minor or can indicate a serious problem. You won’t know until a technician from Merts Heating & Air Conditioning does a diagnostic test.

Things to Check

System problems can also include simply not working correctly, meaning it’s not responding to your settings or is failing to control the temperature in your house. Many times, this will require a thermostat repair or replacement, but there are some things you can try before making that call.

Is it getting power?

If the screen is blank it could mean power is not getting to the thermostat or in some cases batteries need to be replaced. 

Check the wires

If you are comfortable doing so, remove the cover of the thermostat. Examine the wires looking for any loose connections. While you are at it, use a can of compressed air to blow away dirt and corrosion.

Location, location, location

It’s possible the contractor did a poor installation, and your thermostat is in the wrong place. Some guidelines to follow:

  • Not in direct sunlight
  • Not in the kitchen affected by cooking & baking
  • Not adjacent to a fireplace or other heating device
  • Not next to an outside door that is opened often

If location is a problem, you will need the services of a professional to relocate the thermostat.


It’s also important your thermostat is level horizontally and not tilted vertically. It should be mounted five feet from the floor.

Proper setting

Is the thermostat correctly set to the heat or cool position? Please don’t be offended. As simple as it sounds it’s an easy mistake to make and our Merts technicians see it happen often.

Problem Still Not Fixed

If you are still experiencing problems with your thermostat, it’s time to call Merts. Because modern thermostats are electrical there aren’t many parts that can actually wear out, so thermostat repairs are rare. The best option is usually installing a new thermostat in your Illinois or Northwest Indiana house. For more great HVAC information be sure to like and follow us on Facebook and Twitter.