Why Is My Furnace Blowing Cold Air?

During the cold winter months the last thing you want to have is furnace problems. Especially if your furnace is blowing cold air.

There are many issues that can cause your heater to blow cold air. Typically it is best to have an expert come take a look however, below are some common issues that can result in your furnace blowing out cold air.

How To Fix Furnace Blowing Cold Air?

Pilot light out

This is a common issue amongst older furnaces. These older furnaces typically have what is called a pilot light. It is essentially a small flame that is running at all times and is required to light your furnace burners.

Now this is of course if you have an older furnace.

Many new furnaces are much more efficient and have different methods of lighting your furnace. An electric ignitor doesn’t require a pilot light and would act very similar to a gas stove top. It creates a spark, which lights the burners which saves the pilot light from being on at all times.

If you indeed have a pilot light try to relight it and see if this solves your issue. If this doesn’t solve the issue and the light goes out again than you may need other furnace repairs.

Inadequate gas supply

Following up on the previous example, an issue that could cause your pilot light to go out is an not having the proper gas supply.

Check to make sure your gas supply is turned in the on position (parallel/in line with the gas supply pipe.

So Why Is My Furnace Blowing Cold Air Instead Of Heat?

Check The Thermostat

One of the most common causes of a furnace blowing cold air is not actually a repair at all. If you notice your furnace only blows cold air on occasion but your home is still maintaining its temperature than this may be simply a setting on your thermostat.

The fan setting on your thermostat has two options, “on” and “auto”.

The “on” option is exactly how it sounds. Your Furnace Fan will be running all the time even when the furnace system is off. So you will feel air blowing through your vents but the air is not heated or cooled by your furnace system.

Most often this air will feel cold when the fan is “on” but if you don’t notice a change in your overall home’s temperature most likely this is just blowing out room temperature air.

By Switching your settings to “auto” it changes a few things.

First, the furnace fan turns on automatically when your home’s thermostat detects that the house is a different temperature than what has been set. This causes your furnace to kick in and start heating up while the fan circulates the air.

So your fan will only run when your furnace system is running. Should My Thermostat Be Set To “on” or “auto”?

Condensate clog

New high efficiency furnaces have what is known as a condensate drain. It’s job is to remove water that is created during the heating process. This amongst most features in a furnace have sensors that will turn off certain features.

If this drain becomes clogged your furnace may prevent your burners from lighting. This is a good thing.

Clogged filter causes safety control shut off

It’s not uncommon for homeowners to forget about their furnace filters. However this can cause quite a few issues if your furnace filters are not changes on a regular basis.

How Often Should I Change My Furnace Filter?

As filters become more clogged a few things happen. First your filters ability to keep your air clean is reduced causing more contaminants to flow through your air.

Next, it actually restricts air flow that causes your furnace to work harder and if left too long…funny enough… it can actually cause your furnace to overheat.

Eventually this causes your furnace to kick in a safety feature called a limiter switch. This turns off the burners to prevent a fire in your home.

Be sure not to overlook this issue as it can cause damage to your furnaces heat exchanger which can be a costly repair.

High-Efficiency Vent Pipes Are Blocked

On most high efficiency furnaces there are vent pipes that lead to the outside of your home from the furnace. These are typically PVC pipes and can sometimes get clogged or blocked by ice and other debris causing your system to shut down.

Duct work issues

Sometimes ducts may be leaky causing air from cold places like your basement and attic to get into your vents. This can contribute to cooled air in vents and inevitably cause cool air to pass through your heating system.

If you are in need of a furnace repair you can trust our furnace experts here at JPS Furnace & Air Conditioning. We have been servicing Calgary & surronding areas for over a decade With Top-Rated, award winning service.

Proudly serving the Calgary, Chestermere, Airdrie and Cochrane areas.