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Why Is My Furnace Blowing Cool Air?

When the temperature outside is hovering in the 30s or below, the last thing question you want to have to ask is “Why is my furnace blowing cool air?” The answer to that question could be several things, so checking these areas could help you solve the problem and get warm air pumping back into your home.

No Heat? Try these Steps First

Having a broken furnace in the winter can be cold, dangerous and scary. It is definitely something that you want repaired right away. We have a compiled a list of a few things that you can check out on your own first, before calling a furnace company.

The Thermostat: If you walk by a vent and it is blowing cold air, it could be as simple as you have your thermostat set to “on” rather than “auto”.  When it is set to on, the fan will continuously blow even when the furnace is not heating the air and this causes the air to seem cool.  Set it to auto and if it is still blowing out cool air when the furnace is running, it is likely there is something wrong.

The Filter: Whenever you are troubleshooting your furnace, always check and change the filters. An old filter can block the flow of air and decrease the heating ability of your furnace fan as it blows through a dirty filter. In some models, a clogged filter can cause your furnace burner to shut down so it doesn’t overheat, causing a still-running fan to blow cool air.

The Ductwork: Damaged ductwork causes cold air to get into your duct system. Broken or peeling duct tape, broken mastic, or unscrewed ductwork may break or become damaged at the seams, causing them to leak and become inefficient. Even if your furnace is blowing hot air into the ductwork, by the time it reaches the registers, it may only be blowing cool air. These problems should be checked and fixed by a professional to have your heating system working properly.

Windows are not sealed: Did you know that 10% of the money you spend to heat your house is lost through windows? Warm air seeps out in the sneakiest of places. Walk around to each window in your home and check for any drafts or bursts of cold air that you feel coming through. If you notice any air leaks, you’ll want to seal up those windows with caulking. If you’re having a hard time telling where the draft is coming from, grab a lit candle and walk around your house--wherever the flame flickers, you probably have a draft!
Vents are blocked: Every summer, furniture is moved around to accommodate air conditioning or just for a change of scenery. Make sure that your furniture or carpets aren’t blocking your air vents, to prevent warm air from circulating through your home. Not only will blocked vents keep your house cold, but is also a fire hazard.
Gas Valve is Shut Off: While the odds are slim, it’s always a possibility that your home’s gas valve has been shut off. In that case, the furnace will not operate because it’s not receiving gas. Be sure to check your home’s gas valve, and resolve the issue quickly by simply turning the gas back on!

If your furnace is still blowing cool air after your troubleshooting, it’s time to call in the professionals. A.B. May Company is your provider for HVAC services in Kansas City and the surrounding areas. Homeowners have trusted us with their heating systems since 1959. Call us at 913-370-4898 today for help with your furnace.