Why Does My Thermostat Keep Clicking On and Off: Is Something Wrong

The sound is annoying, but what it means can be worse. When your thermostat seems to click on and off endlessly, it’s a sign that something isn’t right, but what? Can you solve it yourself, or do you need to call an HVAC or heating specialist? The good news is that there are often simple solutions to this problem, and many of them you can diagnose and repair yourself with little to no trouble. I will show you all of the most common problems that cause that infuriating clicking issue so you can make it stop faster. In some rare cases, you may need electrical work done, and you may want a professional to handle that, but otherwise, you should be able to solve the troublesome clicking fairly quickly. In fact, the most common solution takes less than a minute to get everything back to normal. You don’t have to live with malfunctioning thermostats and heat or AC problems that can cost you money and unnecessary stress, especially when the fix can be as simple as opening the battery compartment. 

Why does my thermostat keep clicking on and off? Battery-powered thermostats click on and off when the power is getting low. Merely changing out those batteries can be enough to solve the problem until the next time they need a change. However, a few other problems can cause your thermostat to click on and off, such as short cycling, bad placement compressor failure, and electrical issues. 

Thermostat Clicking On & Off Serious Causes and Solutions

Before we take on the simple solutions, I’d like to talk about some of the more problematic causes of a thermostat clicking on and off. While there are a number of easy fixes, some things are probably not DIY. Keep in mind that using off-brand parts and self-repair techniques can void the warranty on your system causing problems and expenses in the long run. 

When Your AC Turns On and Off Immediately

Not all thermostat issues are linked to the AC itself, turning on and off in rapid succession. When it does this, in addition to the clicking thermostat, it’s probably not the thermostat itself causing the problem. Instead, the thermostat is registering activity elsewhere and responding by turning things back on when they self-terminate. 

Run Capacitor

If the thermostat is connected to an outside AC, then checking how it reacts can help diagnose this issue. When your unit turns on and immediately back off again, it signifies a bad run capacitor. In the simplest terms, the power source that ells your ACU to do its job and keep doing it isn’t working as it should. You will probably need this part replaced entirely. 

Electrical Problems (Other)

Numerous electrical issues can arise from a faulty wire to your circuitry. While you will certainly know if the AC/HVAC/Heater switches off and on quickly, it’s harder to be certain that the Run Capacitor, a specific wire, or some other part is the culprit. Unless you are a professional electrician, it’s important to leave these fixes to the pros. By doing so, you can avoid injury or even death, not to mention the minor problem of a voided warranty.

More Potential Thermostat Problems

Sometimes it’s not a simple fix, but the issue also doesn’t cause an AC to turn off immediately. Checking fuel lines to a heater can help, but more often, it’s something else. Refrigerant and fuel leaks, compressor problems, and even having the wrong size unit installed can all change how your thermostat works. 


Does your AC look and feel frozen on the outside. A leak in the refrigerant line can cause this, and it needs to be soldered shut or replaced once it’s located. Similarly, but more dangerous is a gas line leak to a heater. If you have a frozen AC, turn it off, but you need to get out of the house if your gas leaks. 

Compressor Failure

Simply put, the compressor is what makes the cold air. If your compressor is shot, it will make no or minimal cold air available, and that can lead to the obnoxious clicking of a thermostat. When the cooler blows for a short while and shuts down, the thermostat will tell it to work again because it hasn’t finished the job. 

The Easy Fixes For Thermostat Clicking

Sometimes all you need is new batteries or some routine maintenance. Make sure you check the owner’s manual or look up a copy online. Reading through this basic guide can help prevent thermostat problems and costly repairs by providing you with information about what you need to do to keep your system running. 

Condenser Coil Dirt

Routine maintenance and cleaning are necessary. If you haven’t thought about it in a while, you probably need to clean your condenser coils. Skipping over maintenance is something that can happen to anyone when life gets a little hectic. Make sure you add this to your schedule, and it can prevent bigger problems caused by the build-up.

Battery Life

When your thermostat screen goes blank or displays a battery symbol, it’s time to swap those batteries so your temp-reader can keep doing its job. Although this seems all too obvious, a simple dying battery is arguably the most frequent cause of thermostats clicking on and off repeatedly. Naturally, this doesn’t apply to wired-power thermostats. 

Power Outages

Sometimes a heater or cooler has no power, but the thermostat does. A tripped breaker could be the reason your thermostat is clicking. Check to make sure pilot lights are lit on heaters, plugs are in the wall, and the area your heating or cooling device is located hasn’t had a basic power cut. 

Bad Placement

A thermostat that’s not in the right place to correctly sense the overall temperature can be the culprit. From drafty windows or too much direct sun to nearby heat vents and even proximity to a damp, warm bathroom, lots of things can mess with your thermostat. If the location isn’t correct, your sensor may be reading just fine but not getting an accurate idea of the house’s temperature. Rapid changes in the immediate vicinity can make this device click on and off. The practical solution is to relocate it to a more central, less affected area. 

Change Your Filters

A dirty air filter can cause more trouble than you might think. Most air filters need changing every one to three months. A single person, especially one who is out of the house often, may only need a seasonal change, but homes with allergies, pets, or multiple people who are home often probably require a monthly filter change. If your airflow is blocked, then various parts of the system can malfunction. 

When Your Thermostat Needs Replacing

Unfortunately, clicking on and off arent the only two things that can go wrong with your thermostat, though it’s often the first sign. If the batteries and wiring are not the problems, and you’ve checked other components of your heat and AC, it may be time to replace that thermostat. Look out for the following indicators to learn whether your thermostat is out of order. 

Your thermostat may stop turning on or off. When the batteries and power sources are fine, but this part still won’t work, it may be burnt out. Likewise, a dim screen or even a broken screen can be an excellent reason to get a new thermostat.

When your AC perpetually short cycles, the thermostat may be broken. The clicking on and off is a symptom of a larger problem in this case, and you can end up wasting money on power if you don’t get a working model in soon. Similarly, when the temperature gauge is always wrong by more than a degree or two, it might be broken. 

Some thermostats have pre-programmed settings. If yours won’t ‘remember’ the presets, always check the power source first to be sure you aren’t replacing the wrong part. However, a faulty circuit board or other problem could necessitate a new thermostat. 

Final Thoughts

Not every thermostat issue is a huge problem. The more common causes of thermostats clicking on and off repeatedly are fairly simple. From replacing a battery to making sure the setting is correct, some household fixes are so simple, we forget about them simply because they are so minor.

Sadly, some repairs are a bigger deal. If your wiring is bad, or you have an oversized unit, that’s no two-minute fix. Broken compressors and bad run capacitors are still fairly straightforward to replace, but just hearing that you have those problems can seem unnecessarily stressful. Hopefully, your thermostat is clicking for one of the quick-repair reasons, but either way, diagnosing the problem will help you get it fixed.

If the sound of your misbehaving thermostat is too much to handle, you can pull the batteries out or cut the power while you work on solutions. Don’t jump to replace parts too fast, or you may end up doing far more than you needed to fix that click. 

Aron Blake

I am the lead copywriter on Homezesty and the Webmaster. I have a lot of experience in home renovations and the creation of style. I enjoy writing and sharing my tips on how to create the best living environment. My Linkedin Profile, My Twitter Account

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