Though we’re far from the coldest state in the U.S., Tennessee sees its fair share of freezing weather. When the temperatures drop, we rely heavily on our home’s heating: the average home puts a little over one-third of its energy consumption toward space heating.
That’s why it can be so frustrating when your furnace is running but not blowing air. The system’s constant effort means you may as well be burning your money, and you don’t even have a comfortable home to show for it.
Fortunately, there’s plenty you can do to troubleshoot this annoying issue. Here are a few common culprits behind a furnace that won’t warm your property.
Delayed Heating
Before you assume you’re dealing with a broken furnace, make sure you’re giving your system enough time to warm up. This is especially important if you have a larger home or the day is colder than usual, as your furnace may take a while to bring your temperature up to your comfort levels. If you haven’t noticed any warmer air after 15-20 minutes, continue troubleshooting.
Incorrect Thermostat Settings
One of the first steps to take when furnace troubleshooting is checking the thermostat.
If you’ve changed a setting by mistake, you may have disrupted your system’s usual heating patterns. Setting issues are even more common if you live with someone else, as they may have switched the system defaults without your knowledge.
Make sure to check and replace the thermostat’s batteries if it’s been a while.
Verify that the fan setting is set to “auto,” which means that the system will blow air when the furnace produces heat. If you’ve set it to “on” by mistake, the system might keep blowing even when it isn’t heating your home.
If you can recalibrate your thermostat through the settings, do so. The furnace temperature may not be synced right with your home’s current temperature.
Clogged Furnace Filter
A clogged filter might seem like a minor inconvenience, but it can wreak havoc on your system. If your filter has trapped too much debris, it can be hard for your system to work as intended.
In some cases, the clog may even cause overheating, requiring your furnace to blow cold air throughout your home to cool itself down. If the system is overly warm or you smell something burning, stop and contact an expert for emergency furnace repair.
Do a quick furnace filter replacement to see if that solves the problem. Make sure to restart your system after the replacement.
Pilot Light Issues
Do you have a gas furnace? If so, head over to check the pilot light. This component ignites the heater and helps the system provide heat to your home, but it can sometimes get blown out.
Your user manual can help you understand how to reignite the pilot light.
If the light keeps going out, you may be looking at an underlying issue. Dirt and debris can make it harder for the flame to get air, so clean the area around the pilot light to be safe. If this solution doesn’t work, the most likely issue is a thermocouple failure. You’ll need furnace repair services to replace this component.
Not Enough Fuel
Make sure your furnace has enough fuel to power its heating abilities.
If you have an oil furnace, make sure the oil tank is full. For a gas furnace, check the gas valve and open it if needed. If your furnace runs on electricity, look for a blown fuse or breaker.
Dirty Flame Sensor
If you have a gas furnace, a common culprit behind heating issues is a dirty flame sensor. When this sensor becomes dirty, it can be hard for your system to get an accurate reading of your home’s temperature. This may cause it to blow cold air after it’s been on for a while.
Cleaning your furnace flame sensor may help. You can find it near the burner assembly, and it should look like a thin rod. However, you’ll want to be careful not to damage this sensitive component when you clean.
Leaky Ducts
It’s possible that your furnace is providing hot air, but your system may not be delivering that air as intended. If your ductwork is leaky, you may be losing your valuable hot air through tiny openings and crevices. This may cause cold air to blow through the vents of your home.
You may be able to fix leaky ductwork on your own, depending on where the problem lies, but you’ll most likely need a technician’s help. These leaks can be hard to identify and spot, and they often spring up in hard-to-reach areas.
Incorrect Furnace Size
If you’re struggling with a brand-new furnace, the system might not be the right size for your home. In most cases, it will have a hard time measuring your home’s temperature. This can cause it to deliver cool air instead of warm.
You may also notice a higher energy bill than you expected. Furnaces that are incorrectly sized often have problems with energy efficiency, as they’ll work much harder to deliver enough air to your home.
Malfunctioning Components
If none of the problems above seem likely, you may need to have an expert check for a malfunctioning component. A faulty circuit board, loose wiring, or a broken heating element, for example, can cause the system to deliver cold air instead of warm. Another common issue is a high-limit switch failure, which can cause the system to believe that it’s overheating and needs to cool down.
An experienced repair technician can help you identify and repair whatever part needs fixing.
Fix a Furnace Running but Not Blowing Air
When you need to fix a furnace running but not blowing cold air, the troubleshooting tips above may help you diagnose and treat the issue on your own. However, if you can’t find a solution, don’t stress! The expert team at Lanham Mechanical Contractors is here to help.
We serve all of Middle Tennessee and the surrounding areas, and our comprehensive repair services will get your system back to peak efficiency, keeping your home cozy and warm all winter long. To schedule your inspection, contact us online or call us at (615) 880-8879.
