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What Could Cause Cool Air Coming From My Cincinnati Furnace?

Where Is The Warm Air? | Nelson Comfort

A furnace blowing cold air is a troublesome problem homeowners in Cincinnati may experience over the winter. Several issues could be causing such a problem, which we’ll discuss below.

What Causes a Furnace to Blow Cold Air?

  • Clogged air filter: If your furnace filter is clogged from heavy use or because it hasn’t been changed regularly, it can prevent air from flowing through the system correctly. Air is blocked, and your furnace works overtime to provide the heating you need. This can cause the furnace to overheat, triggering the system’s limit switch to turn off the burners for safety. The blower will continue to move cool air through the system to cool the furnace down, resulting in the cold air you feel coming from your vents. If the filter is the source of the issue, replace it with a clean one.
  • Pilot light out: Some older furnaces use a pilot light to ignite burners. If the pilot light goes out, heat will not be produced. If the pilot light will not reignite, a bad or dirty thermocouple could be to blame, requiring replacement.
  • No gas: If the furnace doesn’t receive fuel, it will not create heat. The gas valve may be shut accidentally, damaged, or clogged. If you use liquid propane to heat your home, your propane tank may be out, requiring a refill before your furnace can operate again.
  • Clog in condensate line: New high-efficiency furnaces utilize a condensate drain line that expels water created by the heating process. Clogs cause a backup in this drain, which triggers safety switches to turn off the furnace’s burners.
  • Duct problems: Leaking ductwork can result in great energy loss. If there’s a hole in a duct section, warm air from the furnace will leak out before reaching living areas, and cool air from the unconditioned areas surrounding the ducts will infiltrate them. Duct leaks may cause you to feel cool air blowing from your vents.

These issues can be corrected by an HVAC professional. If your Cincinnati furnace is blowing cold air, call Nelson Comfort for quick, reliable repairs. Our NATE-certified furnace repair technicians are on-call 24/7 to assist you when needed.

About The Author


Dan Detmer

Dan Detmer is the owner of Nelson Comfort. Dan was born into the heating and cooling industry, coming from a family of well respected HVAC contractors in Dayton, Ohio. After working in the family business, Dan decided to work for a local HVAC wholesale business helping local contractors grow their business. When he felt his heart moving him back into the residential and light commercial business, Dan joined the Mortimer Heating & Cooling team in Cincinnati, where he had called home and become part of the community for several years. After a short period of time Dan purchased the company and created what is today, Nelson Comfort. Today he operates a company based on integrity, honesty, and stellar customer service. If you have any questions feel free to tweet (at sign) NelsonComfort and we will get right back with you!

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