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“Help! My Furnace is Running, But It’s Blowing Cold Air”

“Help! My Furnace is Running, But It’s Blowing Cold Air”

Is your furnace running but the air that’s blowing out of your vents seems cold? 

There are a couple things you can do to troubleshoot the problem before calling a heating repair company.

Check the thermostat

You might have walked by a vent and noticed the air seemed cool. But is your home staying warm, at the temperature you set it at? If it is, the problem might be a simple thermostat setting.

Check your thermostat and make sure that it is set to “auto” rather than “on.” When set to “on”, the fan on your furnace will blow continually, even when the furnace isn’t actually heating the air. 

So if you feel the air blowing out of the vents while the furnace is off, the air will seem cool since it’ll be at about room temperature.

Change the air filter

A dirty air filter restricts airflow into your furnace. Restricted airflow can overheat your furnace, causing a safety control to shut off the burners.

This safety mechanism protects your furnace from overheating and the damage that causes.

So change the air filter if it’s dirty. 

Other causes of furnaces blowing cold air

Are you still feeling cold air come out of the vents after trying the above? Your best bet is to have a trusted heating repair company come diagnose the problem. But to give you an idea of what could be wrong, here are other common causes of this problem:

Pilot light/ignition problem

If your furnace seems to be blowing cold air, it could be a problem with the ignition system. Basically, the furnace isn’t lighting the fuel, meaning it can’t heat your home, either.

Inadequate gas supply

Your gas supply could be turned off. Or the gas line isn’t supplying enough gas to your furnace. This can cause your furnace to lock down for safety.

Major duct problems

Large holes and leaks in air ducts can make it seem like your furnace isn’t working. Cold air from your attic or crawlspace gets into your ducts through the holes. 

Condensate clog

New, high-efficiency furnaces have condensate drain lines. Basically, this removes water that is created during the heating process. If the line gets clogged, it can activate a switch that prevents the burners from lighting.

Get your furnace problem fixed

If you live anywhere in the Twin Cities area and your furnace is blowing cold air (or not working at all), MSP Heating can help. Give us a call or contact us online.

We’ve been helping homeowners in the Minneapolis-St. Paul metro area with their heating, plumbing and air conditioning problems since 1916.