Leave a Review
Call Us

Why Is My Furnace Blowing Cold Air?


At this point, we’ve already seen some very chilly weather and even our first snow storm! That means you’ve probably already turned the heat to “on”. If you feel like your home isn’t as warm as it should be, and you’ve noticed your furnace blowing cold air, there are a few reasons why this may be happening.

Here are some things to check/adjust if you’ve detected your furnace blowing cold air –

  1. Thermostat Setting – What is your thermostat set to? If your thermostat is set to “on” instead of “auto” this may be the reason why your furnace is blowing cold air. When set to “on”, your furnace blows air continually. This means even when the furnace isn’t actually heating the air, which causes cool air to come from your vents. If this is the case, changing your thermostat settings is an easy answer to your question why is my furnace blowing cold air.
  2. Furnace filterA Dirty Flame Sensor – If you have a pilotless ignition furnace, then it uses a flame sensor to keep the furnace burning. If this flame sensor is dirty, it can cause your furnace to turn on and begin heating, but then turn cold pretty quickly.
  3. Pilot Light Out – If your furnace still makes use of a pilot light, your furnace blowing cold air could be caused by the pilot light being out.
  4. Dirty Air Filters – A dirty air filter can restrict the airflow into your furnace. When airflow is restricted, this can cause your furnace to overheat. As a safety precaution, your furnace is equipped with a control that shuts off your burner when it is overheated.
  5. Not Enough Gas – Similarly, if your furnace is not getting adequate gas supply (or your gas line is turned off), your furnace will also lock down for safety.
  6. Empty Oil Tank – If you have an oil-fire furnace, you may be out of fuel, which can lead to a continued circulation of cold air.
  7. Furnace maintenance

  8. Duct Issues – If you have large holes or leaks in your air ducts, you may think your furnace blowing cold air means a broken furnace, but this cold airflow could be coming from the cold air getting into your ducts (through these leaks) from your attic or crawlspace. This is very ineffective and energy wasting. Repairing your ducts is important to ensure you are heating your home efficiently.
  9. Neglected Furnace – If you have neglected to clean, repair, and proactively maintain your furnace, chances are it’s having trouble functioning, due to the grime buildup.

These common furnace problems are often the reason for your furnace blowing cold air, and can typically be avoided with regular cleanings and maintenance. If you suspect there is an issue with your furnace, or your notice the furnace blowing cold air, you should call your professional heating specialist so they can first properly diagnose the issue. Once the issue is uncovered, they can move forward with the proper repairs needed to fix your heating system.

Heating your home efficiently is important for the comfort and safety of your family, but also your wallet! As the days continue to get colder, this efficiency is particularly important. Making sure that your heater is receiving adequate oil or gas supply is also something your should be monitoring.

If you notice your furnace blowing cold air, or if it is not working at all, Kulk’s Heating & Plumbing can help. Contact us today!