Why Is My Furnace Blowing Cold Air?

Why is my furnace blowing cold air?

So you’ve turned on your furnace to keep cozy during chilly winter days, but are met with a breeze of cold air—what do you do? Follow these 6 steps to troubleshoot if your furnace is blowing cold air throughout your home. 

  1. Be sure your furnace has warmed up 

Think of your furnace like your car. It has to warm up when you first crank it for it to get going. If you get a cold blast of air when first firing up your furnace, but after a few minutes it begins to warm up, that is nothing to stress over. It is perfectly normal for cool air to blow from the vents while your furnace warms up. Ofcourse, if warm air doesn’t result after a few minutes, follow these next steps. 

  1. Check thermostat settings

If there is a constant flow of cold air blowing from your furnace, check to see if your thermostat is set to “ON” or “AUTO”. If it is set to “ON”, your furnace blower will continuously run even when your furnace isn’t heating the air. Switch your thermostat to “AUTO”, so the fan will only blow when your furnace is heating the air. 

Thermostat auto setting
  1. Check the air filter

A dirty air filter prevents airflow into your furnace, causing it to continuously run and ultimately overheat. When your furnace becomes overheated it signals the safety control to turn off the burners. However, your fan will continue to run, resulting in cold air being blown throughout your home. The solution here is to replace the air filter to return normal airflow to your furnace. 

You may consider investing in a reusable air filter like the Trane CleanEffects air filter that removes up to 99.9% of indoor allergens and never has to be replaced!

  1. Check the pilot light (for a gas furnace)

If your gas furnace is older and is blowing cold air, your pilot light may have gone out. If you are comfortable doing so you can relight your pilot light or call your local utility company or an HVAC technician to make sure it is properly lit. If the light continues to go out, you may need routine maintenance from a heating and cooling professional. 

  1. Reset your system (electric furnace)

Turn the switch on your furnace to “OFF” and wait 30 seconds before turning the system back on. If you have trouble locating the “ON/OFF” switch, you can always turn off power at the circuit breaker level. 

  1. Check your ductwork 

Older ductwork could be damaged or leaking, allowing warm air to escape before it reaches the vents to heat your home. 

If you have completed this checklist and are still having issues with your furnace blowing cold air, it may mean that something more serious has gone array with your system and needs to be assessed by a Carolina Comfort Air HVAC technician. Schedule an appointment today and enjoy $15 OFF your diagnostic fee!

$15 Off HVAC diagnostic fee

We have been proudly serving Raleigh, Fayetteville, Jacksonville, Wilmington, and surrounding communities since 2007 and look forward to helping you with your home heating, cooling, and air quality needs.