Why Cold Air Emits From My Furnace

Cold air emitting from your furnace? Don’t worry. It’s not a ghost. It’s just that your furnace needs to be serviced.

Furnaces are one of the most important appliances in your home. They make sure you have a warm and cozy place to live, even in the frigid winter months. However, when you notice cold air coming out of your furnace, you may start to wonder if something is wrong with it.

There are several reasons why this happens. 

In this article, we will go over some of the most common problems for the furnace blowing cold air and how to fix your furnace. Also, we will give you some tips on when it’s time to call a professional for furnace Installation, Repair, and Maintenance in O’Fallon, Missouri.

What is a furnace?

A furnace is a device or apparatus used for heating purposes, typically in buildings or industrial settings. It is designed to generate and distribute heat, often through the combustion of fuel or the use of electric heating elements.

In residential and commercial buildings, furnaces are commonly utilized as part of a central heating system. They are responsible for heating the air that is then distributed throughout the building via ducts or pipes. Furnaces can be powered by various energy sources, including natural gas, oil, electricity, or even renewable sources such as solar energy.

How does the furnace work?

Your furnace is a complex machine that needs to be maintained and monitored carefully. The following steps will help you understand how it works:


This piece of equipment tells your furnace when to turn on and off. It usually has a temperature dial on it that allows you to adjust the temperature in your home by turning the dial to either higher or lower settings.

Ignition system

This is what actually starts the burning process within your furnace and gets things going. It’s basically an electrical circuit that sends current through some wires connected to a spark plug inside your furnace that then ignites gas when it gets hot enough (or whatever other fuel source you may be using).


This is the part where the fuel gets burned to heat up your home. It’s called combustion because it has two phases: heating up and cooling down. While it’s burning, it releases energy that helps heat up your house.

Heat exchanger

The heat generated by the flame is transferred to the heat exchanger—a metal component within the furnace. The heat exchanger is designed to maximize the transfer of heat from the combustion gases to the surrounding air without mixing them. As the hot combustion gases flow through the heat exchanger, the metal absorbs the heat and becomes hot.

Air circulation

The air circulation process begins with the air intake system, which draws in fresh air from outside and brings it into your furnace. The fresh air is then filtered and heated before being sent through the heat exchanger.

Heating the air

The hot gases from the burn chamber are passed through the heat exchanger, where they heat the incoming air. This is where the magic happens—you can warm up your house with this simple process!

Combustion gas exhaust

The furnace uses combustion to heat your home. Combustion is a chemical reaction between oxygen and fuel that produces heat. In the furnace, the fuel is gas and air that combine in a combustion chamber to produce heat. The exhaust gases are piped out of the furnace through a pipe called a flue.

Thermostat regulation

Thermostats are used to regulate the amount of gas flowing from the source to the burner. They are usually located at the end of the pipe that connects to your furnace’s gas line or gas meter. This helps in controlling how much gas should be ignited at any given time.

Why is my furnace blowing cold air?

Furnace-blowing cold air is a common problem for homeowners. The good news is that it’s often caused by something simple and easy to fix. 

Let’s go over the most common causes of the furnace blowing cold air so that you can call a professional technician for furnace repair O’Fallon, IL, to help you get it back up and running again!

Thermostat Settings

If your furnace is blowing cold air, the problem may be something as simple as setting the thermostat incorrectly. Check your thermostat and make sure it’s set to “Heat” or “Auto.” If it’s not, get a technician to help you with this problem.

Pilot Light or Ignition Problems

If your furnace still blows cold air after setting the thermostat correctly, try lighting the pilot light or resetting the ignitor (if applicable). If none of these options work for you, contact an HVAC professional for more help!

Clogged Air Filter

A dirty air filter can cause cold air to blow from your vents, but replacing it is easy and cheap. If you notice that your furnace is blowing cold air, it’s a good idea to check the air filter first. If it’s dirty, look for a furnace replacement near me.

Blocked Vents or Registers

If you’re still getting cold air after replacing an old filter, there may be something blocking your vents or registers. Check all of these areas to make sure there isn’t anything blocking them and that they’re clear of debris like leaves or snowflakes that could be causing this problem.

Ductwork Issues 

If your ducts are dirty or damaged, they can force your furnace to blow cold air instead of hot. Check your vents in the basement or attic, and make sure they’re clean and in good O’Fallon furnace repair. Also, check for any cracks that may have developed over time. If there is a crack in the ducts, replace them immediately to avoid further damage down the line.

Fuel Supply Issues

Fuel supply issues are another common reason for a furnace not working properly. Check the pilot light and make sure it’s lit when you turn on the furnace. Also, check that there’s enough fuel in the tank for it to work properly. If either of these things is off, fix them before turning on your furnace again!

What to Do When Cold Air Blows from Furnace?

Cold air blows from the furnace. Don’t worry. We’ve got you covered.

We’ve all been there: you’re in the middle of a cold winter night, and suddenly a blast of cold air starts blowing from your furnace. It’s an unwelcome shock to the system and can lead to uncomfortable nights—not to mention that it wastes energy.

Let us walk you through how to troubleshoot and fix this problem using simple steps that anyone can follow.

Check Thermostat Settings

The first thing to do when cold air blows from your heating unit is to verify that you have set the temperature accurately on your thermostat. If you have set it higher than normal, this can cause the furnace to run more often and for longer periods of time—which will cause cold air to blow out instead of warm air!

Verify Air Circulation

If you have verified that your thermostat setting is correct, then it’s time to check for proper circulation in your home. If there’s no airflow through your ductwork or vents, then there won’t be any warm air coming through them—so don’t be surprised if all you feel is the cold wind coming from them!

Inspect the Air Filter

If you’ve had your furnace for more than two years, it’s likely that the air filter needs to be replaced. If it’s dirty or clogged, this could be the cause of your cold air problem.

Verify the Pilot Light or Ignition System

You may want to check your pilot light or ignition system if you have any other problems with the furnace—like not getting hot enough—in addition to cold air blowing from it.

Check the Gas Supply

If you’re experiencing issues with your cold air blowing from the furnace, you first need to check the gas supply. Make sure there’s no blockage and that the gas line isn’t frozen. If there is a blockage or frost, turn off your furnace, clear it out, and then restart it.

Reset the System

If your furnace is working, but the air is still blowing cold, check your thermostat and make sure it’s set correctly. If it’s not turned on or off properly, resetting it should solve the problem.

Inspect for Ductwork Issues

If there are any holes or cracks in your ducts, this could cause cold air to leak out of your vents. The best way to check this is by taking off the cover on one of your vents and looking inside. If there are any holes or gaps in the insulation around the ducts, you’ll be able to see them easily. You can also take off the filter and look for holes there—just make sure not to breathe too much dust while doing so!

Schedule Professional Maintenance

Schedule professional maintenance for your furnace at least once every year—preferably twice per year if you live in an O’Fallon area where winters are more extreme or if you use your furnace more frequently than others do (for example, if you have children who go to sleep early). A professional HVAC technician will be able to identify any issues with your system before they become serious problems that need costly repairs down the road!

How Can Furnace Routine Maintenance help?

The best way to keep your furnace running smoothly is to perform routine maintenance regularly.

Performing routine maintenance can benefit your furnace in three ways:

Improved Efficiency

A clean furnace will run more efficiently, using less energy and saving you money on your heating bill.

Enhanced Performance

A clean furnace will also improve the performance of your system, so it won’t have to work as hard to heat your home. This means that it will last longer and require fewer repairs over time.

Extend the Lifespan of Your Furnace

It’s easy to overlook your furnace, but regular maintenance can aid in keeping it running smoothly and safely. When you schedule routine maintenance, our technicians will inspect your system for problems like corrosion and leaks and ensure everything is working at best. This means your system will run efficiently and safely over time, saving you money on energy costs and extending its lifespan.

Ensure Your Safety

One of the most important aspects of routine maintenance is making sure that your system is safe to operate. When a technician performs an inspection, they’ll check for safety hazards such as insufficient insulation or gas leaks that might lead to a fire hazard or explosion if left unchecked. The safety measures we take during routine inspections ensure that our customers are protected from potential dangers that could exist in their homes—and that’s something everyone can get behind!

Early Problem Detection

Regular maintenance is the best way to keep your furnace in tip-top shape. A tune-up can help you identify problems before they become serious and costly.

Warranty Compliance

Most warranties require regular maintenance in order to be valid. If you’ve never had routine maintenance done on your furnace, you might not be covered for repairs when something inevitably goes wrong.

Peace of Mind

Regularly performing routine maintenance ensures that your furnace is always working at its best and keeps you from having any unexpected issues with your heating system during cold weather months when you need it most!

Call a Professional Furnace Repair and Maintenance Expert in O’Fallon, IL.

If you’re looking for an experienced, professional furnace repair and maintenance expert in O’Fallon, IL, look no further than Stay Cool Climate Control. 

Stay Cool Climate Control is a trusted name in O’Fallon, IL, for all your heating and cooling needs. We’ve been providing expert furnace repair and maintenance services to the area since 2019 and are committed to delivering outstanding service every step of the way.

We can help you with the following:

– Furnace installation and repair

– Furnace maintenance

– Furnace replacement

– Air conditioning installation and repair

– Heat pump repair or replacement

Our HVAC technicians are proud to offer complete heating and cooling solutions–including Furnace Services in O’Fallon. 

When you call on us for help with your furnace or air conditioner, we’ll work with you to create a customized plan that will get your furnace system up and running again as quickly as possible. 

You can also expect the following when hiring Stay Cool Climate Control:

– 24/7 emergency services that are available 365 days a year (including holidays)

– A team of highly trained technicians who are committed to providing expert service and customer satisfaction

– A 100% satisfaction guarantee that ensures all of our customers feel completely satisfied with their experience with us

We strive to be transparent about what repairs will cost before we begin work so that there are no surprises along the way. And if it’s time for an upgrade? We’ll be happy to make recommendations based on your needs and budget!
Call us today at (636) 542-8600, and let us help you with all your furnace repair and maintenance needs.

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