Furnace Not Blowing Hot Air

Is Your Furnace Not Blowing Hot Air? Here’s What It Means

Is Your Furnace Not Blowing Hot Air? Here’s What It Means

Winter's always means the temperatures may drop dramatically where you live. Maybe they already have, considering we're in St. Louis!

But not to worry; all you have to do is turn the heater on, and you're set. Or that's the idea, at least.

Is your furnace not blowing hot air? Then you may have some issues at hand. Keep reading to find out what may be the issue if it's not blowing hot air, and what to do about it.

Why Is My Furnace Not Blowing Hot Air?

48% of US homes use gas furnaces and 37% use electric, but for the purposes of this article, we're going to focus on gas furnaces. Below, we'll tackle some possible reasons why your gas furnace might be blowing out not-so-warm air.

Your Thermostat Setting Is Wrong

This may seem like a painfully obvious reason for why your furnace isn't blowing hot air, but you'd be surprised at just how many people don't check their thermostat first before calling an HVAC expert.

The first thing you should look at is the fan setting. If it's set on "on," then it'll continually blow at all hours of the day. This is why you're feeling colder air come through. To fix this, just switch it from "on" to "auto."

In most cases, just flipping the switch will make your furnace blow hot air again.

If that doesn't fix it, then you should take a look at the temperature setting on your thermostat. Is it set to higher than the current temperature in your house? If not, then that's your problem.

This problem may sound like a silly one, but if you live with others, you may not be aware of them fiddling with the temperature settings without you knowing. So it's always a good idea to check. Plus, it just takes a second to do!

If there's still no difference after changing the temperature, or you see that the setting's already higher than the current temps, there's one more thing you can try. Check the batteries and replace them.

Still no hot air? Then you possibly need to have your thermostat recalibrated or replaced.

You're Not Waiting Long Enough

Just as a car takes a little bit to warm up, so will your HVAC system. This is especially true if you have a large home.

We understand you're really cold and you want to be warm pronto, but sometimes, all you have to do is give it a little time. Before you pick up the phone to call an HVAC company, give it some time for it to push out the cold air and hopefully fill up your rooms with hot air.

Do note that it's completely normal for your furnace to first blow cold air before it gets hot.

Your Filter's Dirty

When's the last time you replaced your furnace's air filter? If the answer's "never," or "years ago," then this may be your culprit.

Your furnace needs a clean and clear air filter to circulate hot air efficiently. Over time, debris, dust, and allergens build up on these filters, which eventually, causes them to clog.

So if your furnace is blowing cold air, you'll want to check your air filter. Once you've taken it out, hold it up to the light. If you can't see any light shining through, then you definitely need to change it. A good rule of thumb is to change it every 6 months; if your house gets a lot of foot traffic, and/or you have a lot of pets, then you'll want to make that every 3 weeks.

The Pilot Light's Gone Out

If you have a gas furnace, then it relies on a pilot light so the heater ignites and provides heat for your home. It's supposed to stay on at all times, but it can end up blown out in some circumstances. For instance, if your local gas company has recently done maintenance or there was an emergency, these situations can cause your pilot light to go out.

In this case, you'll have to go check your furnace. If the pilot light is out, then you can try relighting it by yourself. You may have to refer to the furnace's manual to do it correctly.

If the pilot light goes out again pretty soon after, then you can also try cleaning the pilot light. Often, dust and debris builds up, which can cause a bad connection.

If the cleaning doesn't seem to help, there's one more thing to try: check the gas supply line. If this is the first time you're using the furnace in a while, you may have forgotten that you closed the gas supply line during the summer. It should be simple to open it back up.

Do none of the above solutions solve your problem? Then you might need to replace the thermocouple. This can be something you can DIY, but considering it involves sensitive equipment, you should probably leave this job up to a qualified professional.

Your Flame Sensor Is Dirty

Perhaps your furnace isn't sending out consistently cold air. Instead, maybe it's warm for a little bit, then it gets cold after a while.

If this is happening to you, then the flame sensor may be dirty. If it is, it'll provide inaccurate temperature readings, which is what's causing the furnace to throw out cold air after it's been on for a length of time.

Thankfully, it's relatively easy to clean your flame sensor. All you need to do is cut the power, remove the flame sensor, clean it with an Emery cloth (don't use sandpaper!), then reattach it.

Once you've done this once, then you can keep up it for practically forever. This, combined with a great HVAC maintenance plan, can keep your furnace running smoothly.

Your Ducts Aren't Sealed

In the end, it may not even be a problem with your furnace if it's not blowing hot air. Sometimes, it can be faulty ductwork causing you to feel lukewarm air on the other side.

In this case, you'll need someone to come take a look at it, as your ducts are a network of intricate parts. Not to mention, you'll probably have to go on the roof to check them out.

The worst-case scenario is there are holes in your ducts, which is letting cold air in. Otherwise, your ducts may just need a thorough cleaning. If they're stuffed up with debris and dirt, it may be causing your furnace to overheat, which would make it shut down and blow cold air.

When to Call a Professional

While some of the above issues can be quickly fixed by yourself, there are larger problems that are best left to the professionals, even if you have some handyman experience.

You may be tempted to try and handle things on your own, but this may lead to bigger, more expensive problems. Not to mention, it may be hazardous to your health as well.

Here are a few instances where you need to call a professional promptly.

If You're Not Sure What You're Doing

There are certain instances where you can certainly try and fix things yourself, but it may not always be the best idea. If you don't feel comfortable with what you're doing, always stop what you're doing and wait for a professional instead.

When you're not confident in your DIY skills, pushing forward can lead to costly and dangerous mistakes.

You Have a Gas Leak

Over time, some cracks can appear in your furnace. As a result, you may have a gas leak in your home.

If you notice a rotten egg smell at any time, you need to immediately switch off the gas and get out of the house. Prompt action is crucial; if there's enough gas buildup, it can result in an explosion. Not to mention you may get carbon monoxide poisoning as well.

So if you even suspect a gas leak in your home, don't try to do anything on your own. Instead, focus on getting your family out and call a professional straight away.

Make Sure Your Furnace Is in Working Order This Winter

If you've been scratching your head and wondering, "why is my furnace not blowing hot air," you now know a few reasons why. If it seems like a small and easily fixable issue, then go ahead and try to troubleshoot it yourself with the tips we've given you.

However, if it seems like there's something larger at play, don't try to pinch pennies and either ignore the problem or try to DIY it. Considering most furnaces involve propane or natural gas, this is something a professional should take care of. Because they're properly trained, experienced, and licensed, they'll ensure the problem is found and fixed in a safe manner.

Do you need someone to come take a look at your broken furnace? Then get in touch with us now to make an appointment.

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