Why is my furnace blowing cold air?

The last thing you want in the winter is to find that your furnace blowing cold air out. Cold air blowing out from your furnace doesn’t necessarily mean you need to call an HVAC technician ASAP. There are quite a few reasons why your furnace is blowing cold air that you can easily fix yourself. 

Check the thermostat

While it seems like the obvious answer, there are a few things you might be overlooking. 

  • Make sure your thermostat is set for heating and not cooling
  • Check the fan setting. If it’s set to “on”, it may be circulating air continuously whether it’s been heated or not. Change it to “auto” so that it’s only blowing warm air into your home.
  • Compare the temperature setting to what you’re actually feeling in your home. You may need to increase the temperature for more comfort. 
  • If you have a programmable thermostat, check to see if the temperature settings are correct for when you’re at home and away

Check your furnace filter

If you find your furnace blowing cold air, it might be due to a dirty furnace filter. A clogged filter can restrict airflow enough to make it seem like cold air is blowing through your home. If it’s incredibly dirty, it could also cause your furnace to overheat and shut down. The fix to this is simply to replace your filter or clean it if it’s reusable. 

Is it time to call an HVAC professional?

Unfortunately, there are certain things that you can’t fix yourself that you’ll need professional help with. A few this issues include: 

  • Fan limit switch malfunction – A faulty fan limit switch can cause your furnace blower to circulate cold air when the furnace isn’t heating or it can cause the furnace to shut down completely
  • Flame sensor malfunction – If you notice your inside temperature is much cooler than what you have your thermostat set at or your furnace keeps turning on and off, it could be a malfunctioning flame sensor
  • Leaking ducts – If air from your registers is cooler or the flow is weaker than normal, it could be due to leaking ducts that need to be repaired or replaced
  • Pilot light is out – If you have an older furnace (pre-1990s) it might be blowing cold air or shutting down because the pilot light is out. If this is the case, you may be able to fix this yourself by finding the manufacturer’s instructions for your unit and simply re-lighting it. 

Is your furnace blowing cold air?

Not sure why? Give our HVAC team a call and we’ll provide the solutions you need to help stay warm this winter. 

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