When winter weather rages and the temperature drops, your home’s heating system is more important than ever. And there’s nothing worse during the most brutal stretch of winter than discovering your furnace blowing cold air. Fortunately, there are a few things you can do to get your home warm and toasty again, and fast!

We’ve rounded up five common problems that cause furnaces to blow cold air, along with troubleshooting tips to get warm air blowing again.

INCORRECT FAN SETTING

When faced with a problem, always start with the easiest possible solution. In this case, the thermostat fan setting. If the fan is set to “on”, it will blow air continually, whether or not the furnace produces heat. Move the setting to “auto” and see if that resolves the issue.

DIRTY FURNACE FILTER

If your furnace completes a full cycle but the air never quite warms up, it could be due to a clogged furnace filter. While one might think that a blocked filter would prevent air from coming through the vents, the blower will still push air through them. The blower normally draws air through the filter and across the heating element. But if that path is blocked by a dirty filter, the air will move through any crack or gap in the furnace body or vent system. Check your filter and replace if needed. And be sure to change it regularly (about every 8 weeks or so) to keep your heating system running effectively and efficiently.

IGNITOR OR PILOT LIGHT ISSUES

Gas furnaces use an ignitor or pilot light to spark natural gas into flame. If the ignitor fails or pilot light goes out, the heat will fail to kick on and instead the furnace will circulate cold air until the system recognizes a problem and shuts down. A faulty ignitor will need to be replaced whereas an extinguished pilot light can be relit. However, if it continues to go out, it may need cleaning or replacement.

DIRTY FLAME SENSOR

If your gas furnace begins to blow cold air, then cuts off abruptly, it could be the flame sensor. If the furnace cycles up but the sensor fails to detect the flame’s heat, it will shut down the furnace to prevent gas from entering your home. This essential safety feature can collect debris on its surface, giving a false alarm, and end the cycle before the circulating air can move from cold to warm. The sensor will either need to be cleaned or replaced.

CLOGGED CONDENSATE LINE

A furnace connected to a central AC system (as well as all high-efficiency gas furnaces) has a condensate line that allows excess water produced by the AC and furnace to drain away from the unit. If dirt or debris block the line, water will back up and trigger a shut-off safety switch or interfere with or damage the furnace. In either case, the furnace may not light and instead blow cold air, then shut down.

Are you having issues with your furnace? Or perhaps it’s time to upgrade to a new energy-efficient unit. Whether it’s furnace repair or new system installation, our team of HVAC professionals is ready to assist. Contact C&D Cooling & Heating today for more information or a new system proposal.