Can a home thermostat go bad? 

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faulty home thermostat

A thermostat is an important part of your home’s heating & cooling systems as it controls and monitors the temperatures in your indoor spaces. To be precise, the thermostat detects the room temperature and compares it to the desired temperature setting. Best of all, it will either heat or cool the air, depending on whether the room is too cold or too warm. But can a home thermostat go bad? 

Well, like any other electric device, your home thermostat will either malfunction or become outdated. So, yes, your thermostat will certainly go bad at some point. As you’d expect, a malfunctioning system will have some negative impact on your HVAC system. For instance, the entire system can stop functioning at all, or you’ll note a significant increase in your energy bills and reduced comfort. 

On the bright side, faulty home thermostat symptoms are relatively easy to troubleshoot. In this article, I’ll show you some common home thermostat issues and how to fix them! 

What are the symptoms of a bad home thermostat? 

  • My home thermostat has no power 

One of the most popular signs of a bad thermostat is if your device is unresponsive or doesn’t have power. However, this can also be caused by other issues like dead or weak batteries. If that’s the case, try using lithium batteries and reset the thermostat to power it up. Alkaline batteries can cause malfunctions and inconsistencies in your device since they run out of power quickly.

 If replacing the batteries doesn’t fix the problem, check if there is a disconnect in their thermostat circuit board or electrical wiring. Also, check the breakers since your thermostat will not have power if one of the HVAC system’s breakers has tripped. 

  • The home thermostat not reading the correct temperature 

Another obvious sign that your thermostat is failing is if its thermostat reading doesn’t match the room temperature. However, this is completely normal if you’ve got a multi-zone heating system in your home. That is because a multi-zone setup divides your home into zones, and the thermostat only controls specific areas within the zone. 

Other than that, if your thermostat experiences constant jumps in temperature between rooms, check if it’s faulty. Simply put, the thermostat should have the same temperature reading throughout various parts of your house unless you’ve got a multi-zone or ductless AC system. 

  • The heater or Air Conditioner won’t turn on 

Typically, if your HVAC system does not turn on or respond to the thermostat, you will notice a temperature difference in your apartment or home. This is a clear indication that something might be wrong with your home thermostat. To troubleshoot the problem, look at your thermostat settings to determine if your heater or air conditioner is running. On the same note, change the settings of the thermostat to see if you’ll get any response from your AC, heat pump, or furnace. Also, inspect the furnace or AC unit to see if they are running by extracting or drawing in air through the vents. 

If you notice a clicking sound but your HVAC system doesn’t turn on, your thermostat might be having a wiring defect, control board issue, or a broken relay. Any of these issues will prevent electrical signals from being transmitted to your heating and cooling system, preventing it from turning on. 

  • Your heater/ AC runs continuously 

Another indication that your home thermostats may be having issues is if the HVAC system doesn’t stop running after setting it to turn off. As a result, it will continue running, even when your house is at the right temperature. 

Alternatively, a faulty thermostat can make the HVAC system shut off before it completes a cooling or heating cycle, and turn on again after a short time. This shows the temperature sensor of your thermostat is failing. Unfortunately, short cycles shorten the lifespan of your HVAC system. The same case applies when the system is running continuously since it overworks, which can eventually damage it. 

In some instances, your HVAC system may be running continuously because of a dirty air filter. As a result, the system will run without reaching the desired temperature since it’s not drawing the air it needs. 

However, if that’s not the cause, the wiring within your thermostats may be failing. Also, this problem can be a sign of miscalibrated thermostat settings, thus sending incorrect signals to the heat pump, furnace, or air conditioner. 

Troubleshooting a bad thermostat

Now that you know some bad home thermostat symptoms, let’s look at 5 simple steps that will show you how to tell if a home thermostat is bad! 

  • Check the batteries

As mentioned earlier, the first thing you should do if you’re having problems with your thermostat is to check the batteries. To accomplish that, remove its faceplate to expose the batteries underneath. If the batteries are weak, replace them with new lithium batteries. If possible, replace your thermostat batteries every year to ensure this problem doesn’t occur. 

  • Adjust the thermostat settings 

Sometimes, the thermostat reverts to factory settings, either due to a power outage or tripped circuit breaker. To avoid jumping to conclusions that the thermostat is bad, try adjusting its settings to see if it’s working correctly. For instance, adjust its settings to either 5 degrees higher or lower depending on the season. If the thermostat is not bad, you will hear a click as your HVAC unit is adjusting to the new temperature. More importantly, set the thermostat settings to ‘Auto’. This will help your HVAC system only run when it’s either heating or cooling the air. 

  • Check the circuit breaker

Another thing that might be preventing your thermostat from turning on is if the HVAC system tripped the circuit breaker. To find out, head to the circuit breaker box and look for the Air conditioner or furnace circuit. If the circuit breaker is tripped, flip it back on and test your HVAC system and thermostat. 

  • Clean your home thermostat 

If you’re still using a manual thermostat, you can quickly troubleshoot it by cleaning it. This will help to remove any dust that may have accumulated in its analog lever, causing it to malfunction. To accomplish this, remove the cover of your thermostat and dust its level with a microfiber cloth or toothbrush. Next, gently clean the thermostat using compressed air. However, don’t use this troubleshooting method if you have a digital thermostat. 

  • Test the wiring connections 

Lastly, wiring connections used in thermostats tend to become loose, dirty, and old over time, causing the device to malfunction. So, if your thermostat seems faulty, remove the cover and check if all the wires are firmly connected to the corresponding mounting screw. Make sure you turn off the circuit breaker before you remove the cover to avoid being electrocuted. Alternatively, contact a professional HVAC technician to test each wire individually to determine which one needs to be replaced. 


If your thermostat still doesn’t work after performing the above troubleshooting solutions, you should probably consider installing a new one. Luckily, there are some incredibly smart thermostat options out there to choose from. Even better, here is a detailed review of some of the best smart thermostats you’ll come across in the market at the moment! 

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