HVAC Repair: How to Detect and Fix a Bad Thermostat

Detect and Fix a Bad Thermostat

Generally, thermostats don?t have a particular set lifespan. However, the average lifespan of a thermostat could be 10 years. After this period, the thermostat may start malfunctioning because of dust accumulation or aging wiring. Read on to see how to detect a bad thermostat and how to fix them.

How to Detect a Bad Thermostat?

Here are some of the signs of a bad thermostat. 

A thermostat is unresponsive or out of power

If after adjusting your thermostat and the home?s temperature remains the same, or the display is not responsive, it could be that the thermostat is broken, or you need to change the batteries. Also, if your air conditioner or heater won?t turn on, then know that the thermostat wiring needs to be corrected. 

Fixing or Troubleshooting A Thermostat

If you have noticed any of the conditions stated above, then follow the following steps to fix or troubleshoot your thermostat. If it does not work perfectly, bring in your local engineer.

  • Check that the thermostat is on the right setting. This step is an obvious one to take, however, you need to be sure that the thermostat is set on ?cool? if it is summer, or ?heat? if it is winter. If the heater or air conditioner is running constantly, it may be set to ?ON?, set the thermostat to ?AUTO? so that the cooling/heating system does not run always.
  • Turn the thermostat down up by 5 degrees. Depending on the season you are in, any of these two could work: turning the temperature higher than normal in winter, or setting it lower by 5 degrees in summer.
  • As soon as you turn the thermostat up or down, listen to hear a click. Then, wait to get the reaction if the supply register blows out the air or sucks in the air.
  • For an electronic or digital thermostat, try replacing the batteries. Thermostat batteries should be replaced at least once every year. 
  • For mechanical thermostats, clean the thermostat. If the thermostat you have is the type that is controlled by a lever, then know it is a mechanical thermostat. They could malfunction due to much dust, so take your time to clean them. Remove the thermostat cover and clean the inside with a small cloth or brush.
  • Test and check the wires and wire connection. Open the thermostat cover to see if the wires are well connected. Ensure they are attached to their respective screw.

If you have checked and all these listed troubleshooting is well okay, maybe it’s time to invite your professional to check the issue. Remember that playing around with the wires is dangerous, so a certified HVAC engineer should be contacted to fix this issue for you.


Thermostats don’t usually go bad, but when they do, ensure you follow the proper procedure for fixing them. If you cannot troubleshoot the issue by yourself, ensure you invite a professional heating and cooling company. It is dangerous to tamper with devices you don?t know much about to avoid further havoc and unnecessary spending.

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