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Why Is My Furnace Blowing Cold Air?

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If your furnace isn’t heating your home properly and is blowing cold air through the vents, there is most likely a problem with one of the four main components needed to make it work.

9 Reasons Your Furnace Is Blowing Cold Air

  1. You aren’t giving it enough time – your furnace needs some time to heat up, especially the first time it’s used after many dormant months.
  2. The pilot light is out – when your pilot light is out, your furnace can’t effectively heat your home. A professional HVAC company can ensure it’s properly relit.
  3. It’s out of fuel – if there is no fuel being fed into the furnace, it will only blow cool or cold air. Gas valves need to be open and oil tanks must be filled in order for the fuel to get to the burners. Even electric furnaces need fuel—electricity. Make sure the electric breakers are flipped to the “on” position, and make sure the outlet isn’t overloaded.
  4. Your filter is dirty – When your filter is dirty it can block the airflow, leaving only lukewarm or even cool air actually making it to some rooms in the house. Some furnace models even shut down the burner when the filter is clogged in order to avoid overheating, leading to cold air blowing through.
  5. You have clogged burners – Oil furnaces are especially in danger of this mishap, where the burner can clog with dirt and debris. It is possible to clean a clogged burner yourself, but it’s best to call in a licensed technician.
  6. Your ductwork is leaking – if there are leaks in your ductwork the hot air will seep out through the holes. Whatever air doesn’t leak out through holes will be cold be the time it gets to the rooms in your home.
  7. You have a faulty ignition – a burned out thermocouple or faulty ignition can stop the fuel supply to the burners. If you suspect a faulty ignition or a bad main gas valve, play it safe and call a professional to repair it.
  8. There’s a problem with your thermostat – if nothing looks amiss with your actual furnace, it may be a problem with your thermostat. Make sure your fan is switched to “auto” instead of “on.” The “auto” setting will make sure the fan only blows when the furnace is on.
  9. The flame sensor is dirty – if the sensor is dirty then the heat will turn on but become cold relatively quickly.

Furnace Blowing Cold Air? Call Michael Bonsby HVAC for Repairs!

If you live in Maryland or Washington, DC and your furnace is blowing cold air, Michael Bonsby Heating & Air Conditioning can help. We provide furnace repair services in and around the Montgomery County area to get your system up and running fast. Call 301-990-7970 to schedule service today!

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