Signs of a Faulty Thermostat

August 25, 2018

Thermostats regulate the temperature in your house. If you notice your house is staying hotter or colder than the temperature you have set, you may have a faulty thermostat. Go through the following steps to rule out common problems before replacing the thermostat.

Programmable Thermostats

  • Check that your thermostat is in the on position and that there are no programming overrides in place.
  • If your thermostat uses a battery, replace it and see if it starts functioning properly.

Older Thermostats

  • If you have an older thermostat, check the manual switch for adjusting the temperature. If it feels loose, it won’t be accurately setting the temperature and the thermostat should be replaced.
  • Check all the switches and buttons to make sure there are no broken pieces.

Force Your System to Turn On

  • In heating mode, set the thermostat 10 degrees warmer. You should hear your thermostat click on as the furnace starts to run. Go to the furnace and verify that it turned on.
  • In A/C mode, set the thermostat 10 degrees colder. You should hear your thermostat click on as the air conditioner starts to run. Go the air conditioner and verify that it turned on.


  • Breakers – If either the furnace or air conditioner doesn’t turn on, check the breakers for each unit and make sure they have not tripped. If they are tripped, reset them, and then go check to see if the units are now running.
  • Dust – Open up the thermostat and check for dust build up. Use canned air to clean out all the dust.
  • Loose Wires – After the dust is gone, look for (but don’t touch) any loose wires. If you see a loose wire, you will need to turn off the breaker to the thermostat and reattach it. Always consult a user manual or contact a professional, if you are unsure.
  • Call a Professional – If the air conditioner or furnace still won’t turn on, the wire from the thermostat to the unit may be broken, or the heating or air conditioning units themselves may have an issue. Call a trained professional to determine the problem.

If you need help with your thermostat or HVAC unit, call Reddi today at 316-462-2572 to schedule an appointment.