Winter 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 that require furnace repair. 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 this article will focus on gas furnaces. Below, we’ll tackle why your gas furnace might be blowing out not-so-warm air.
Your Thermostat Setting Is Wrong
It may seem painfully obvious why your furnace isn’t blowing hot air, but you’d be surprised how many people don’t check their thermostats before calling an HVAC expert.
The first thing you should look at is the fan setting. If it’s set on “on,” it’ll continually blow at all day hours. This is why you’re feeling colder air coming through. To fix this, switch it from “on” to “auto.”
In most cases, flipping the switch will make your furnace blow hot air again.
If that doesn’t fix it, you should 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 silly, 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 no difference after changing the temperature, or you see that the setting’s already higher than the current temps, you can try one more thing. 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 freezing, 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 to push out the cold air and hopefully fill up your rooms with hot air.
Note that it’s normal for your furnace to blow cold air before it gets hot.
Your Filter’s Dirty
When was the last time you replaced your furnace’s air filter? If the answer’s “never” or “years ago,” this may be your culprit.
Your furnace needs a clean, 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, you need to change it. A good rule of thumb is to change it every six months; if your house gets a lot of foot traffic and you have many pets, you’ll want to make that every three weeks.
The Pilot Light’s Gone Out
If you have a gas furnace, it relies on a pilot light, so the heater ignites and provides heat for your home. It’s supposed always to stay on, but it can be blown out in some circumstances. For instance, if your local gas company has recently done maintenance or an emergency, these situations can cause your pilot light to go out.
In this case, you’ll have to check your furnace ignitor. If the pilot light is out, you can try relighting it yourself. You may have to refer to the furnace’s manual to do it correctly.
If the pilot light goes out again soon after, you can also try cleaning the pilot light. Often, dust and debris build-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 your first time using the furnace, 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. You can DIY this, but considering it involves sensitive equipment, you should probably leave this job 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 bit, and then it gets hard after a while.
If this happens to you, then the flame sensor may be dirty. If it is, it’ll provide inaccurate temperature readings, which cause the furnace to throw out cold air after it’s been on for a long time.
Thankfully, it’s relatively easy to clean your flame sensor. You need to 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, you can keep it up practically forever. This and an excellent HVAC maintenance plan can keep your furnace running smoothly.
Your Ducts Aren’t Sealed.
It may not even be a problem with your furnace if it’s not blowing hot air. Sometimes, it can be faulty ductwork, causing lukewarm air on the other side.
In this case, you’ll need someone to 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 holes in your ducts, which let cold air in. Otherwise, your ducts may need a thorough cleaning. If they’re stuffed up with debris and dirt, it may be causing your furnace to overheat, making it shut down and blow cold air.
You Have A Blocked Burner
Over time, burners can get blocked or clogged, preventing fuel from passing through. The burner will not ignite, and the furnace cannot produce heat without fuel. But a blocked burner does not affect the fan, so the system will continue to pump cool air through the vents and out into your home.
You Have A Wrong Sized Furnace
Size does matter. If you have a new furnace system and are confused about why it’s not blowing hot air, your heater is probably too small for your home. Your furnace can blow cold air if not appropriately sized for your home. You will also experience problems with efficacy and efficiency if it is too small or too huge.
If your furnace system is too small for your home, it may blow cool air because it can’t get a decent read on its internal temperature. On the other hand, too huge furnaces will unexpectedly turn on and off.
Your issue here is either confusion about the mechanics or a lack of power. Understanding the proper furnace size is crucial, especially as the cooler months approach.
Your Furnace Lacks Fuel
If your gas furnace is not blowing hot air and fails to ignite, the issue could be with your gas supply. Either the gas valve is broken, or the gas tank has to be refilled. If you use propane instead of natural gas, your gas supply will run out over time, and you’ll have to fill it regularly to keep your home warm.
Your Furnace System Has Overheated
If your system only blows cold air, there’s a possibility that your furnace system has overheated. But you don’t need to worry because this usually does not indicate the broken unit.
When the system overheats, a safety feature turns it off. This is beneficial since it can prevent a fire, carbon monoxide leak, or even an explosion. Even if the furnace’s safety switch is turned off, it may still vent cold air briefly. The entire system, though, will eventually shut down.
There are several reasons why a furnace may overheat, including:
Old Age of the System
Your furnace’s age can be a factor in why it overheats. Your furnace’s performance will start to deteriorate as it gets older. While parts may wear out over time, your system should last roughly 15 years. It may, however, fade out much sooner if you do not follow preventive maintenance guidelines. If your furnace is old and overheats frequently, its age could be the source of the problem.
Mechanical Failure
Since a furnace has so many moving components and processes, it can break down anytime. This is especially true if your HVAC system is older. While a mechanical failure can cause various problems, overheating is one of the most typical.
Dirt Buildup
A clogged filter is one of the most common causes of a heater blowing cold air. However, even if you replace the air filter with a new one, dirt, and other particles can still be inside the system. This could lead to overheating in the long run. If your furnace seems to be dirty, contact an HVAC company for a thorough, professional cleaning.
Troubleshooting Tips For Furnaces Not Blowing Hot Air
If your heater isn’t blowing hot air, you may be suffering from one of many common furnace problems. Consider the following furnace troubleshooting tips:
- Inspect your thermostat’s fan settings to see whether they’re “auto” rather than “on”.
- Ensure your thermostat has not been set to a lower setting by someone else.
- Check your thermostat’s batteries and replace any that are exhausted or defective.
- Clean all of the parts of your furnace, especially the ones that are susceptible to dust and dirt. You could also hire HVAC technicians to clean the system thoroughly.
- Ensure that the gas valve is open and not obstructed by any debris.
- Make sure to shut the blower motor panel after cleaning or repairs.
Consider Regular Furnace Maintenance To Prevent Your Furnace From Blowing Cold Air
Nobody enjoys shivering. Thankfully, you have a furnace system, so you’ll never have to worry about a sudden cold spell again! Showing a little tender loving care for your furnace by giving it regular maintenance can help you ensure that you will always enjoy hot air whenever you want it.
Problems that cause your heater to spew cold air can be avoided or repaired with regular furnace maintenance before you lose heat. During an annual maintenance checkup, a professional HVAC expert will inspect and adjust all wiring, switches, and connections.
The technician will also tighten connections, clean each component, and decide whether any parts need to be changed throughout this process. The thermostat, heat exchanger, pilot light, main limit switch, evaporator coil, and furnace filter will all be checked during this process.
When to Call a Professional
While some of the above issues can be quickly fixed by yourself, more significant problems 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 more significant, 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
You can certainly try and fix things yourself in certain instances, 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.
Pushing forward can lead to costly and dangerous mistakes when you’re not confident in your DIY skills.
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, immediately switch off the gas and leave the house. Prompt action is crucial; if there’s enough gas buildup, it can be an explosion. Not to mention, you may get carbon monoxide poisoning as well.
So, if you suspect a gas leak in your home, don’t try to do anything alone. Instead, focus on getting your family out and call a professional immediately.
FAQs: Furnaces Not Blowing Hot Air
Why is my furnace running but not blowing hot air?
The short answer is that we can’t say for sure because it depends on your situation. There could be several reasons your furnace system is not blowing hot air. Sometimes, the problem can be minor, and you can resolve it independently. However, having a professional inspect and fix the system is still best.
What do I do if my furnace is blowing cold air?
If your furnace isn’t blowing hot air and is blowing cold air, some problems can be easily solved with only basic technical furnace repair
knowledge. You can resolve some of these problems independently with some research and effort.
Unfortunately, several issues will necessitate more advanced knowledge, which you can obtain from your local Carrier dealer. A competent HVAC technician has the skills, knowledge, and experience to handle more complex electrical, mechanical, or fuel supply problems.
Why is my heat not getting hot in the house?
There are several reasons why your heat isn’t working. The type of heating system you have, how old it is, and a range of other factors will all play a role in determining the cause of the problem. However, there’s no need to worry about a complex heating problem when you can resolve it quickly by contacting our HVAC experts. And if your furnace is not blowing air, it’s time to call in the professionals.
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 why. If it seems like a minor and easily fixable issue, try troubleshooting it yourself with the tips we’ve given you.
However, if there’s something larger at play, don’t try to pinch pennies and either ignore the problem or try to DIY it. A professional should handle this since most furnaces involve propane or natural gas. Because they’re adequately trained, experienced, and licensed, they’ll ensure the problem is found and fixed safely.
Do you need someone to come to look at your broken furnace? Crystal Heating and Cooling is the best heating and cooling company in St. Louis.
Request a service call with us now to make an appointment.
