Furnace Blower Keeps Running But No Heat Coming

In wintertime, the last thing you want to do is come back to your house and discover that your furnace blower keeps running but no heat comes out of your furnace. There are a few things that can keep your furnace blower running without heat coming out. These include, incorrect thermostat settings, ignition problems, problems with heating elements and clogged air filters.

How Does a Furnace Blower Work?

It is worth noting that a furnace blower doesn’t produce heat instead, a blower is responsible for circulating the air in your furnace. This is what a blower fan does in your furnace.

• It draws the air in into your furnace through the return air ducts
• Pushes the air through the heat exchanger
• Forces the air into the ductwork for circulation into your home

So clearly, the blower fan has no hand in the process of heating the air. But then, why would your blower fan be running without pumping out any heat? When you have a situation such as this, you might want to start troubleshooting your heating system, right away.

In this article, we have put together common reasons you have a blower fan running without heat coming into your home. So, read on to learn more.

5. Possible Reasons Your Furnace Blower Keeps Running but No Heat Coming Out

1. Thermostat Not Correctly Set

When you have any heating issues with your furnace, the first thing you have to check is your thermostat. A lot of times it happens that the thermostat is not set correctly.

One of the commonest reason your furnace blower will be running but no heat coming out is when your thermostat is not set to ‘heat’ mode. This sounds unlikely but it happens often than thought. This is what you should check with your thermostat

• Make sure that the thermostat is set to heat. On top of that, your fan setting should also be set to auto. Your furnace blower is probably running with no heat because of your thermostat settings.
•  Make sure your fan is set to ‘auto.’ If its set to ‘on,’ it will keep blowing air  when the furnace is not producing heat. It could be why your furnace is not blowing hot air.

2. Ignition Issues

After having checked with your thermostat settings and there is no heating coming through, then let us move to another step in troubleshooting your furnace.

No heat coming from your furnace could mean that there is an ignition issue with your furnace. Let’s briefly look at how your furnace heats up the air to help us better understand what can prevent ignition in your furnace.

• Natural gas is ignited in the burners to produce heat
• Of course, for ignition to take place there must be gas supply
• The pilot light is the responsible for igniting the gas on the burners.
• If the flames sensor doesn’t detect the presence of flames within seconds, it will close the gas valve to prevent the leaking of the gas.

Read also: Why is my furnace short cycling

This is what could cause ignition failure in your furnace

• There is no gas coming through. You need to check if the gas valve is open to ensure free flow of gas into your furnace. If the handle for the valve is in line with the pipe, then the valve is open, Other wise if it is perpendicular to the pipe, this means it is closed and there is no gas coming to your furnace.
• The pilot light not working properly. The pilot light is responsible for igniting the burners. If the pilot light is not coming on or is not working properly, then your furnace will have problems igniting. if not ignition take place in your furnace, there will be no heat produced and the only thing your furnace will blow is the cool air that was drawn into the system.
• Dirty flame sensors. Flame sensors are another safety feature for your furnace and are located in front of the burners. If flame sensors can not detect flames on the burners, they will quickly shut off the gas valve. This safety measure prevents gas from leaking into your home.

Solution to ignition issues

Many furnaces come with built in reset buttons and by resetting your furnace, you can clear most heating issues from your furnace.

If you are using a gas or propane furnace, you can reset your furnace by:

• Using the reset button. But in some cases, you may need to follow the user manual for resetting your furnace.
•  You can also reset your electrical furnace by turning it off on the circuit breaker and wait for about 5 minutes before turning it on Again.

For furnaces with the pilot light, you will need to make sure it is on, other wise you need to find out how to reset the pilot light for your model, usually by going through the user manual.

For your pilotless furnaces, you will need to replace the ignitor if your furnace won’t come on after resetting it.

3. Problems with Heating Elements:

After you have tried resetting your electric furnace and the furnace doesn’t give you heat, the problem could be the heating elements. When your heating elements are dead or not working, you will need to call in professional service to come and take a look. Heat elements might need a replacement.

4. Clogged Furnace Filter

Actually, the next you need to check after ruling out thermostat issues is your furnace air filter. Dirty of clogged air filters cause a lot of issues with your furnace.

Open the return vent and look at the condition your air filter. If it’s dirty. Replace it with a clean or new one. Make sure you note its size before replacing it.

Government recommends changing air filters monthly or as advised by your manufacturer.

5. Broken or Misaligned Belt Can Cause Furnace Blower to Run Without Heat Coming Out

If you have tried troubleshooting with the above tips and your furnace blower keeps running but no air comes out of the vents, the problem could be a broken or misaligned belt which is not turning your fan.

You can easily solve this problem by calling an HVAC to come and take a closer look.

FAQ

How long does it take for furnace to reset?

Resetting your furnace takes about 5 to 10 minutes. You can reset your furnace by  turning off the circuit break for up to 10 minutes before turning it on again.

Final Thought

When your Furnace blower keeps running but no heat comes out, it could be due to any of the issues we have looked in this article.

To prevent future furnace issues, you should make sure you have maintenance tune up twice a year. During maintenance tune up, a technician can come and examine your furnace and other components that are prone to wear.

Tim David

HVAC tech with over 30 years of experience. Retired and doing repair work on the side around Madison County, AL.