Your furnace is running, but instead of warm air coming through the vents, you’re getting the cold shoulder. On a freezing Indianapolis day, that goes from strange to concerning pretty quickly. Sometimes there’s a simple explanation you can check yourself, while other times a furnace blowing cold air is a sign that something inside the heating system isn’t working properly and only a certified HVAC professional can fix it.
In this blog from Honest Abe’s Heating & Cooling, we’ll walk through what to check, what different symptoms can mean, and when it’s time to call for furnace repair.
Why Is My Furnace Blowing Cold Air?
If your furnace is blowing cool air or room temperature air instead of warm air, something may be interrupting the normal heating cycle. Possible causes include:
- A faulty thermostat or fan set to ON can keep the blower fan running when the furnace isn’t actively heating.
- A dirty filter or clogged filter can restrict airflow, cause overheating, and trigger a safety mechanism that shuts the burners off.
- A dirty flame sensor or other flame sensor issues can cause the burners to ignite and then shut off within seconds because the furnace can’t confirm a flame.
- An ignition failure can prevent a gas furnace from lighting the burners and producing heated air.
- On an older furnace with a standing pilot light, a pilot that won’t stay lit can prevent the burners from operating.
- A faulty control board can interfere with the sequence that controls the burners, ignition system, and unit’s fan.
- Repeated overheating can shut the burners down while the blower continues running, helping cool the furnace and protect components such as the heat exchanger.
Regardless of what’s causing the problem, we know you just want it fixed so your furnace can get back to heating the house.
How Can I Fix a Furnace Blowing Cold Air?
You can safely troubleshoot a heater blowing cold air when the possible cause involves something you normally use or maintain yourself, such as the thermostat or air filter. If the problem seems to go beyond these things, it’s time to stop and call an HVAC technician.
What you can do yourself ultimately depends on the symptoms and where the problem is coming from. The checks below can help you figure out whether there’s something you can correct or whether your furnace needs a professional repair.
Troubleshooting a Furnace Blowing Cold Air
Cold air from the vents doesn’t always mean something major has gone wrong with your furnace. There are a few safe things you can check yourself, and sometimes one of them is all it takes to find the problem. Start with these four checks and see what your furnace does.
Look At the Air Filter
Pull out your furnace filter and see how dirty it is. A dirty air filter restricts airflow, and a badly clogged air filter can cause some furnaces to overheat and shut the burners off while the blower keeps running. If you can see a heavy buildup of dust and debris, replace the filter with the correct size and type.
Double-check the Thermostat
Make sure your thermostat settings show HEAT and that the temperature is set higher than the temperature currently displayed. Then look at the thermostat fan setting and choose AUTO rather than ON. Incorrect thermostat settings can leave the fan circulating unheated air even though the furnace isn’t in the heating process.
Open Your Vents
Walk through the house and make sure the supply registers haven’t been closed or covered by furniture, rugs, or curtains. Closing too many vents can reduce airflow through the system and, in some systems, contribute to overheating and a safety shutdown of the burners. Open them back up and give the furnace a few minutes to run through another heating cycle.
When to Call a Furnace Repair Company
If the basic thermostat, filter, and airflow checks don’t solve the problem, the cause is likely somewhere inside the furnace. At that point, a certified HVAC professional can safely test the components responsible for producing and controlling heat. Call for furnace repair if:
- The vents start blowing cold air and never switch over to warm air during the heating cycle.
- The furnace produces hot air at first but quickly turns cold before the thermostat reaches the temperature you’ve set.
- Your heating system repeatedly starts, stops, and tries to heat again without successfully warming the house.
- You hear the furnace start but the burners fail to ignite or ignite briefly and repeatedly shut back off.
- You smell gas in or around your home. Leave the area, avoid switches or anything that could create a spark, and contact your gas utility or emergency services from a safe location.
When it’s 20 degrees outside, you don’t want to spend time troubleshooting a furnace blowing cold air or worse. Honest Abe’s is available for your furnace repair in Indianapolis if your checks haven’t revealed anything.
Honest Abe’s Is At Your Service
Honest Abe’s Heating & Cooling is a local Indianapolis HVAC company with years of experience helping families through all kinds of furnace problems. Whether your furnace is blowing cold air, shutting down halfway through a cycle, or not producing heat at all, we’re ready to find the problem and make the repair.
If you can’t troubleshoot the issue yourself, or you simply don’t want to mess with it, please contact us. Your furnace is what stands between your family and a freezing-cold night, and we don’t want you sitting in the cold waiting for the heat to come back. Call Honest Abe’s and let us get warm air moving through your home again!