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“Why Is My Furnace Blowing Cold Air?” [FAQ]

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furnace-2Here’s a bone-chilling question we see often,“Why is my furnace blowing cold air?”

We’ll explain a few common causes of this annoying problem. While we can’t promise we can help you fix it on your own, at the very least you’ll know what the contractor is talking about if they come by to help.

1) Thermostat is set to “ON” instead of “AUTO”

If your furnace’s fan is running constantly and is only producing heat sometimes, the problem may be with your thermostat setting.  If you have your thermostat set to “ON,” your furnace’s blower runs constantly—even if it’s not heating the air.

Make sure your thermostat is set to AUTO, which will cause the furnace to only blow air out of your vents when the furnace’s burner has ignited.

2) Pilot light isn’t lit

If your furnace is only blowing cold air, the pilot light may not be lit.

Inspect your furnace pilot light and relight it. If the pilot light won’t stay lit, the thermocouple may need replacing. There are a variety of other technical issues that could be causing this as well. So you’ll need to call a heating technician to fix it.

3) Gas supply problems

If your furnace isn’t getting any gas, the furnace has nothing to burn. So the heat exchanger can’t get hot and warm up the air blowing over it. That’s why your furnace would only blow cold air.

A few things prevent gas from getting to your furnace. Your furnace’s gas valve may be closed. When the gas valve switch is parallel/in line with the gas supply pipe, then it’s in the “on” position—right where you want it.

If the gas valve switch is perpendicular, then it’s in the “off” position and no gas can reach the furnace. It may have been switched off for a previous repair.

Also, whoever supplies your gas may be having problems. Contact your gas supply company to see if they are having any issues.

If your furnace is still blowing cold air and you need help, contact Air Professionals for help

Air Professionals is a whole-home comfort company serving New Jersey homeowners. Contact us for more information on how we can help improve your home’s comfort.