Why is My Furnace Blowing Cold Air?

Open Gas FurnaceOne of the most common furnace problems reported each winter by Framingham-area homeowners is a furnace that seems to be blowing cold air.

There could be a variety of reasons your furnace is blowing cold air and they range from very simple to quite complex.Here are some of the most common causes of this problem.

It’s Normal.

If the air coming out of your vents is only cold when it turns on but heats up after a few seconds, this is normal operation.

For example, when you turn on a hot water faucet, it takes a little time for the hot water travel from the water heater to the spout. In the same way, when your furnace turns on, it must clear out the cold air already in your vents.

Your Fan is Set to “On.”

Many Framingham-area residents turn on their heating system for the winter and then notice they are being treated to a constant flow of cool air. This isn’t a problem with your furnace – it’s your thermostat.

Make sure your fan is set to “auto” rather than “on”. “Auto” will only turn on your fan when your furnace is running. “On” will keep your fan running at all times (or until turned off.)

Your Pilot Light is Out.

For homeowners with older gas furnaces, a furnace that only blows cold air can be a sign that the pilot light has gone out. Re-light the pilot light to solve the problem.

If the pilot keeps going out, contact a heating professional – your furnace may need some routine cleaning.

The Flame Sensor is Dirty.

Another common complaint is furnaces that turn on and begin heating but then the air turns cold again very quickly. Most of the time this is a dirty flame sensor that is not allowing your furnace’s burner to remain lit.

Get a heating professional to clean the sensor. This is one of the reasons annual furnace maintenance is so important.

It’s More Technical.

Your furnace is a gas appliance with many moving parts. The items above are the most common, but there are many other things that can cause your furnace to blow cold air, such as a bad ignitor or malfunction on the circuit board.

If you need further help diagnosing the reason your furnace seems to be blowing cold air, contact a Framingham-area heating company like Nicholson HVAC.