Skip to content
Available 24/7!  Call or Text Us! 

Why is My Furnace Blowing Cold Air? Common Answers for St. Louis Area Homeowners

small_4240912364Our furnaces are supposed to keep us warm, so it can be very concerning when you put your hand over one of your air vents and realize that your furnace is blowing cold air! This can happen for a number of different reasons, and the solution will depend on your specific situation. Today we’re going to talk about some of the most common reasons why your furnace might start blowing cold air and what you can do to fix the problem!

 

Why is my furnace blowing cold air?

 

    • You need to wait a few seconds. If you feel cold air coming out of your vents right after your furnace turns on, this is completely normal. The air in your ducts will cool down when your furnace is not in a heating cycle, and that cool air will be pushed out of your vents when your furnace turns back on. Wait a few moments and see if that cool air is replaced by warm air. If not, you might be experiencing one of the issues below.

 

    • There is an issue with your thermostat’s settings. Another problem that can cause your furnace to blow cold air is that you are using the wrong thermostat settings. First, check to ensure that your thermostat is in the “heat” mode. If it’s not, then your air conditioner might be running instead of your furnace. Also, check to see if your fan setting is set to “on” or “auto.” If your fan is set to “on,” then your furnace will circulate air even when it’s not heating that air, which will cause cooler air to come out of your vents.

 

    • Your furnace’s sensor is dirty. Your furnace has a sensor that detects whether or not your burners are indeed lit. If the sensor does not detect a flame, it will shut your burners off as a safety precaution in order to stop gas from being fed to your system. Sometimes sensors can get dirty, especially if you haven’t scheduled a furnace tune-up or you have a dirty filter installed. If your sensor is dirty, it will not be able to detect a flame properly and it will shut your burners off, causing your furnace to start to blow cold air. A dirty sensor should be taken care of by a professional like Jerry Kelly.

 

    • Your pilot light went out. If you have an older furnace with a pilot light, the flame can sometimes blow out. When this happens, there is nothing to ignite your burners and your furnace will blow air that’s not heated. Try relighting your pilot light to see if that fixes the problem, and contact Jerry Kelly if the problem persists.

 

If you have any questions about a furnace blowing cold air, or if you’d like a heating system serviced or installed in your home, contact Jerry Kelly, your St. Charles, MO, furnace installation and repair contractor. We service the St. Louis area, including towns like Weldon Spring, Wentzville and Winghaven, MO.

 

photo credit: jamelah via photopin cc