How Do You Fix A Furnace Fan That Keeps Running

When the blower fan of a furnace keeps running continuously it is a sign of a problem which should be taken care of as soon as possible by heating repair services. However, you should know the reasons why it happens and the things that you can do to fix it.

Check The Thermostat Settings

The furnace keeps running issues could be because of incorrect thermostat settings. Therefore, check the settings of your thermostat first when you identify that the furnace is running without cycling off.

You should focus on two things when checking the thermostat settings. Firstly, the thermostat fan settings should be on AUTO. If the setting is at ON, switch it to AUTO because the ON button forces the furnace to keep blowing air until it is switched back to AUTO. Change the settings and wait for a few minutes to check if the furnace cycles off.

The second thing to check is the temperature settings. Sometimes, a furnace doesn’t turn off because the set temperature is too high and the weather outside is too cold so the furnace keeps heating and blowing hot air continuously to reach that temperature. If the temperature is too high, set it to low and notice any changes.

Ensure The Fan Limit Switch Is Not On Manual Mode

The fan limit switch controls the functioning of the furnace blower. You can find it inside the panel cover of your furnace.

When the fan limit switch is set correctly and working in optimum condition, it turns on the blower a few minutes after the thermostat sends the signal for heat and turns off the fan a few minutes after the heat cycle ends.

So, check the fan limit set and make sure it’s not on the manual settings because it will overall the thermostat settings and make the blower run continuously. You can check it yourself if you have knowledge of the furnace you have. See inside the furnace’s hood and you’ll notice a white button. It is the fan limit switch.

The button should not be pushed in because it means the manual mode is on. Push the switch out to switch it to the AUTO mode. If not sure, simply try to push the button out and check the furnace.

If you can’t find the fan limit switch, let a furnace technician check this for you and also change the settings if it is in manual mode.

Faulty Fan Limit Switch

A malfunctioning fan limit switch can also be the cause of the blower fan running all the time. You would have to replace the fan limit switch as soon as possible with an expert to fix the problem. This will also ensure an inspection from the expert who will be able to tell you more about the issues and also spot other problems if any.

Other signs of a faulty fan limit switch:

  • The furnace starts blowing cool air
  • The furnace begins short cycling (turns on and off in short intervals)

Thermostat Wiring Problems

If the wires in the thermostats short out they won’t be able to send signals to the furnace when to stop and start. This can keep the furnace running without stopping. You should inspect the thermostat and get it repaired or replaced for fixing the problem.

Fan Limit Switch Wiring Issues

Similar to the thermostat wiring, if the fan limit switch wiring is shot, it will stop the fan limit switch’s control over the fan. So, the fan may run continuously. You should perform repairs or replacement of the fan limit switch.

Furnaces Require Regular Maintenance

If you don’t want your furnace to break down in the middle of the night when it’s freezing outside, ensure regular maintenance. Replace the air filters, clean the air ducts, change the thermostat batteries, and follow the user manual for best results.


When a furnace doesn’t stop and keeps running all the time, the causes of the problem are the thermostat or the fan limit switch. An inspection can show if you only need to change their settings or if they are faulty and require replacement. Make sure to hire furnace repair services DC for fixing your furnace problems.

Is It Normal For A Furnace To Run Nonstop

Having a furnace in your house to keep you warm and cozy when it is freezing outside is a blessing. However, just with anything, furnaces tend to experience problems as well. A common problem is that the furnace runs constantly. While it depends on the temperature, the furnace should not work continuously to maintain the temperature and you should check it yourself or by furnace repair services.

So, we are going to take a look at why your furnace might be running nonstop and what you can do about it.

Blower Issues

The first thing you need to check if your furnace is running nonstop is the blower. If you notice that the furnace is running but is blowing cool air, it means there is some issue with it. It might be that there is a shortage somewhere that is causing the blowers to malfunction.

Although, you can inspect the blower for any corroded wires or damage, etc. but do not attempt to fix the issue on your own. You can end up electrocuting yourself.

Dirty/Clogged Filter

If you observe that the air coming from the vents is warm but the airflow is weak, it means the filters are most likely clogged. Furnaces come with filters installed as well just like the air conditioners. These filters make sure toxicants are removed from the air before it is distributed inside the house.

As a result, these filters are prone to getting dirty and clogged with time. Furthermore, clogged filters prevent the necessary air from moving into the furnace. This leads to a failure in reaching the desired indoor temperature.

Consult the user’s manual and check the replacement or cleaning interval. It might be that the filters need to be replaced. So, make sure you opt for the exact replacements.

Thermostat Issues

Next, you will need to check for thermostat issues. Ensure that the thermostat is to “ON” settings instead of “Auto”. The reason is that if the settings are set to “ON”, the furnace might run constantly. However, if it is turned to the “Auto” position, the furnace should turn off as soon as it reaches the required temperature.

But if you notice that the furnace keeps running considering the thermostat settings are correct, it means that there is something wrong with the thermostat. In this case, you will need to consult a specialist who will replace it for you.

Pilot Light Issues

If you own an older furnace, it might have a pilot light that stays lit as long as the furnace is on. If that is the case, you will observe your furnace only blowing cool air and running constantly. So, if the pilot system has some issues, it might be causing the furnace to run constantly. You will need to contact a specialist to fix the issue.

The Furnace Is The Wrong Size

Another possible reason for your furnace to be running non-stop is if it is of the wrong size. This is one of the most common problems out there as homeowners ignore this basic factor. An wrong sized furnace will not be able to tackle a room that is either too small or big.

Choosing the correct furnace size is critical. This is why buyers are suggested to measure the room size and purchase the furnace accordingly. If the room happens to be big but the furnace is small, it will run constantly to achieve the desired temperature. This would only lead to higher energy bills in the future.

How Often Should My Furnace Cycle In The Winter?

The winter season can give your furnace a tough time. After months of being dormant, your furnace suddenly finds itself working overtime. So, it will undergo some stress. Prepare your furnace for winter before using.

Furnaces are designed to cycle multiple times during the day. However, if it cycles throughout the day, it might indicate a problem. There is no universal answer to how many times your furnace should cycle in a day. But it should not be cycling throughout the day. Anything between 3 to 8 times per hour is considered normal.

Final Word

In the end, a furnace running non-stop is not something normal. If that is the case, you will need to follow the tips mentioned above or consult furnace services Long Island if the situation seems more complicated.

Why Is My Furnace Not Shutting Off

It is often that you come across a furnace that simply refuses to shut off. A continuously running furnace not only increases the energy costs but might soon develop problems as well. You should call in furnace services if your furnace is not shutting down. In this blog, we are going to take a look at some important factors contributing to this problem and how you can solve them.

Check Your Thermostat

The first thing you need to check if your furnace is not shutting off is the thermostat. A thermostat measures the inside temperature of your house and tells the furnace to increase or decrease the production or circulation of hot air accordingly. If it happens to be faulty, it will confuse the furnace.

As a result, the furnace will continue working and the temperature inside your house will not reach the desired temperature. Even though thermostats giving up is rare unless they are very old, that does not mean it is not possible. In other cases, you might need to calibrate it. Either way, fixing up the problem does not break your bank but ignoring it will increase the energy costs in the long run.

To check whether the thermostat is working fine, you should set it to On or Auto. If you set it to Auto, the fan will automatically shut down once the adjusted temperature is achieved. In addition to that, if the temperature is set too high, the furnace might not be able to keep up, causing it to run continuously. Upon running an inspection there seems to be no problem with the thermostat, you should move on to the next step.

Check Your Air Filter

No matter how much you stress it, some homeowners still ignore the air filters. The air filters are installed in the furnace for a reason. The primary job of the air filters is to filter the air and then distribute it. Since air passes through the air filter, they are prone to get blocked or clogged. Therefore, it is always advised to clean the air filters at least once or twice a week.

In some cases, you might need to replace the air filter as well. Ignoring a clogged air filter will lead to toxic air making its way inside your house and causing serious respiratory problems to your family members. Depending on the area where you live, you should regularly inspect the air filters. If that is not possible, hire a professional to do it.

Check The Ductwork

The ductwork is a system through which hot or cold air passes to the inside of the house. Overtime, duct leakages can develop, causing both hot and cold air to escape. As a result, the furnace will continue working to keep up with the adjusted temperature. There could be several reasons contributing to leaky ducts. Birds and rats can build accommodations for themselves, which can sometimes lead to cracks and damages.

Unfortunately, fixing damaged or cracked ductwork is not something you can do on your own. In some cases, the leaks are so minor that it is hard for a new person to notice. Therefore, the problem will require a thorough inspection. With that said, you should call upon a professional who will inspect the unit find the main issue and fix it.

Check The Fan Limit Switch

You will be able to find this part inside the furnace panel cover. It is designed to turn on and off the blower at appropriate times. Therefore, if the fan limit switch happens to be working perfectly, it should turn on the fan when the thermostat signals heat and turn off a little after the end of the heat cycle.

However, if you notice that the furnace fan keeps running regardless of the furnace heating or not, your fan limit switch is either set incorrectly or faulty.

Final Word

Concluding, the tips mentioned above will surely help you fix your furnace that fails to shut off. A furnace is an expensive unit and ignoring such minor problems can lead to a replacement, which is a costly procedure. Therefore, if you fail to solve the problem, do not hesitate to call in furnace repair services Long Island.