What to Do When Your Furnace is Blowing Cold Air

A furnace sometimes acts as the lifeblood of any home or venue. On those cold winter nights where the weather looks to dampen spirits, a furnace breathes warm air into open spaces and puts a smile on everyone’s face. 

As magical as it sounds, sometimes things don’t always go to plan. There are moments when your furnace is blowing cold air, and maybe you simply don’t understand how that’s even possible or, worse, what to even do about it. That’s why we’re here! We here at Crystal Clean Vents have wrestled with our fair share of furnaces, and we’re going to break it down so you know what might be happening. 

What Are The Potential Reasons Why My Furnace is Blowing Cold Air?

There are many potential reasons why your furnace is blowing cold air, and we’re going to explore them all to give you a better understanding of what your issue might be. 

#1 - Leaking Air Ducts

A major contender for furnace issues is leaking air ducts. This can be due to disconnected pipes, holes, or leaks that allow the hot air to escape before reaching the vents. If you’ve got a rodent infestation, then they could be adding to the issue of holes in pipes, so ensure you consider this as a possibility and investigate further. 

Faulty furnaces are one thing, but rats are a whole lot worse. If you fix the problem before figuring out what caused it, you might find history repeating itself. Contact us for a free air duct assessment today.

#2 - Incorrectly Set Thermostat

Suppose the heat isn’t present when you activate your furnace. In that case, one of the first things you need to consider is that the thermostat hasn’t been appropriately adjusted. This can happen for a variety of reasons:

1. Someone unfamiliar with properly setting a thermostat.

2. You haven’t adjusted for different seasons. Look at our guide to thermostat settings in Utah seasons for more information.

What you’re going to want to do is have your furnace set on Auto. If your furnace is just always On, then what ends up happening is that your fan blows even if the furnace itself isn’t on. This means that cold air will get circulated because the furnace isn’t on to warm it up.

#3 - Dirty Furnace Filter

If you have to think long and hard about when you last cleaned your furnace, then it’s likely it’s been too long. A dirty furnace filter is probably the biggest culprit for why your furnace is blowing cold air. 

Clogged air filters end up with limited airflow to the heat exchanger, which can cause overheating. When this happens, the furnace limit switch may be tripped, shutting down the heat exchanger entirely.

#4 - Clogged Condensate Line

A condensate line moves water further away from the actual furnace. When it’s clogged, it prevents the furnace from igniting. If a clogged condensate line causes a lack of ignition, you’ll find only cold air is emitted. 

#5 - Overheating

When furnaces overheat, they shut down. It will emit cold air for a moment, but this is only temporary as eventually it just shuts off altogether. This can be for a variety of reasons;

1. Age

2. A build-up of dirt

3. Mechanical failure

Furnaces get old, and often, people don’t realize until it’s far too late. So it stands to reason that with age comes difficulty. If you’re wondering why your furnace is blowing cold air, consider when you actually had it installed. There’s little to fix when it comes to aged furnaces, and you’re probably better off replacing it altogether. 

A build-up of dirt is some of the previously mentioned reasons; dirty filters, clogged condensate lines, other foreign items, or dirt blocking elements of the furnace. A thorough inspection and detailed cleaning will be required. Take a look at our 7 tips for furnace maintenance to avoid this.

Mechanical failure can be an aging issue as well, or perhaps a result of overworking the furnace. This might mean simply replacing a part or two or replacing the entire unit. 

#6 - Gas Supply Issues

There are many issues relating to a gas supply that could potentially answer why your furnace is blowing cold air. Suppose the furnace pilot light isn’t instantly going out or perhaps no lighting whatsoever. In that case, gas supply issues are the first place to look.

You might simply not have enough gas in the tank to fulfill the task your furnace is designed to do. However, if the pilot light isn’t working at all, it might be the gas valve. Please, and we cannot stress this enough, do not attempt to fix this on your own. Call the professionals like us!

#7 - Faulty Pilot Light

If you’ve got an older furnace, then a pilot light is lit right from the gas line. Relighting a pilot light is only something you should do if you’re 100% comfortable and read the instructions carefully. 

On the other hand, replacing a pilot light is dangerous and something you need to be extremely careful of doing. Refer to the manual the furnace came with and ensure you completely understand what is being asked of you. If, however, it’s the gas valve, once again call the pros. 

If you’re ever wondering why you should consider getting your furnace serviced, read our blog post on the ‘Reasons for a Furnace Tune-Up’ here.

What To Do When Your Furnace is Blowing Cold Air

Here are just a few things you can do on your own if your furnace is blowing cold air.

#1 - Fan Settings

In the event of an improper fan setting, the best course of action is to:

1. Review current fan settings.

2. Ensure the switch is set on Auto.

When the setting is on auto, you shouldn’t have issues with cold blowing air. If your furnace is blowing cold air even after this change, it’s not a setting issue.

#2 - Check Air Filter

In the event of an improperly functioning air filter, the best course of action is to;

1. Find the furnace’s filter compartment.

2. Slide out the old filter, and toss it out.

3. Replace it with a new, same-size filter and ensure it’s positioned properly.

#3 - Pilot Light Isn’t Functioning Properly

In the event of an improperly functioning pilot light, the best course of action is to;

1. Shut off power to your furnace.

2. Locate and turn off the reset switch.

3. Let the escaped gas clear for roughly 15 - 20 minutes.

4. Turn reset switch to pilot. At the same time, use matches or a lighter at the end of the pilot to light any outgoing gas.

5. Once the pilot is relit, turn on and restore power to the furnace.

Final Thoughts

While there are so many moving parts to a furnace and potential reasons as to why your furnace is blowing cold air, it’s not something to panic over. While there are easy fixes that you can do on your own, some might require a more professional approach.

If you’re in need of that professional approach, then you need Crystal Clean Vents. We’ve been doing this for over two decades, and we know furnaces like the back of our hands. So, if you want to experience, reliability, and professionalism, don’t be scared to get in touch with us today!