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Why Is My Furnace Blowing Cold Air?

January 20, 2023
Wrapped in blanket on couch

What is your favorite winter activity to do in Charleston? Some favor escaping the cold weather and snuggling up on the couch, while others enjoy the cold during an off-season beach walk. However, what do you do if you return from a winter activity to your furnace blowing cold air? An Anchor Heating and Air technician can quickly identify and repair the problem, but it is important to remain knowledgeable on your furnace system. In this blog, we discuss potential causes of why your furnace is blowing cold air.

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Much like any heating and cooling system, furnaces require repair from time to time. Furnaces are complex systems and one obstruction can cause the whole system to quit working. Some furnace repairs can be a simple fix, while others require professional help. If your vents are blowing cold air, there could be many causes. Below are five potential reasons your furnace is distributing cold air in West Ashley and surrounding areas.

  • Malfunctioning Thermostat
  • Clogged Condensate Line
  • Dirty Air Filters
  • Pilot Light Issue
  • Low Gas Supply

Malfunctioning Thermostat

As silly as it may seem, double check the status of your thermostat if you are experiencing furnace problems. Someone in your home may have accidentally switched the thermostat setting and caused your furnace to blow cold air. Ensure the thermostat is set to your preferred temperature and on “Heat” mode. Next, confirm the thermostat is set to “Auto” rather than “On.” Thermostats set to “On” cause the furnace to run constantly, whether or not it is generating heat. If both of these settings are correct, the thermostat may need new batteries or is experiencing an internal malfunction.

Clogged Condensate Line

Furnaces not only work to provide heat for your home, but remove moisture as well. Due to the furnace operation process, condensation can form and exit through a drain line. Condensate lines can become clogged from dirty coils or mold growth inside the line. Blocked drain lines can deactivate furnace burners or pilot lights and cause cold air to be distributed into your home. Additionally, clogged condensate lines can cause water leaks and not only damage your furnace, but your home as well. It is best to give one of our trained technicians a call to properly unclog the condensate line and prevent any further issues.

Helpful tip! Your drain line need to be flushed at least twice a year. As a member of the Captain’s Club, you’ll receive annual furnace maintenance which includes flushing your drain line.

Dirty Air Filters

Air filters are one of the most important components of your home’s heating and cooling systems, because the filters catch allergens and increase many aspects of the heating process. Not only do air filters increase air quality, but airflow, comfort, and efficiency as well. If your furnace is not blowing warm air, we recommend checking the status of each air filter in your home. Dirty air filters strain the heating system, because of its inability to push air through the filter pores. An overworked system can lead to a breakdown or the unit shutting off completely, which would be why your vents are distributing cold air. Additionally, it is important to not forget about the furnace filter! Furnace filters are located in the blower compartment and need to be regularly changed with filters around your home.

Pilot Light Issue

Pilot light issues are a common cause of furnaces generating cold air, but our technicians can quickly fix the problem! Pilot lights are a small blue flame that serves as the ignition source for a gas burner. If the pilot light goes out or experiences a malfunction, heat will never be produced. If the pilot light is out, the furnace will circulate cold air until the unit recognizes the issue and shuts down completely. If the pilot light is an orange or yellow, it indicates there is a gas problem. Too much gas can cause health issues and risk your safety, which is why pilot light problems should never be ignored.

Low Gas Supply

Natural gas furnaces are the most common type of furnace. If your home uses a gas furnace, it requires a steady supply of gas to generate heat. Furnace systems are designed to shut off if there is little to no gas, which is why you may experience cold air coming from air vents until the unit shuts off. Interfering with natural gas can pose a threat to your health and safety, and we do not recommend attempting to repair the problem yourself. Our technicians are well-trained in repairing gas furnaces in Summerville, South Carolina!

Being knowledgeable about your furnace can help identify if the furnace repair is a simple or professional fix. If your furnace isn’t blowing warm air, consider these common causes. Let us help you keep your home warm and cozy this winter season with our furnace repair services in Mount Pleasant and surrounding areas.

To learn more about the furnace operation process and types of furnaces, visit our recent blog article “Heat Pumps vs. Furnaces.”

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Written By Stephanie Postell

Stephanie is the Co-Owner and COO of Anchor Heating and Air and is a lifelong resident of Charleston, South Carolina. Stephanie and her husband David have over 30 years experience in heating and air conditioning.

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