Most Common Reasons Your Furnace Blows Cold Air

Posted: 2019-03-14

During the cold months of the year, your furnace is probably the most important piece of equipment in your home. It is the main device that gives you warmth in the midst of extremely frigid weather. Most homeowners even operate their heating systems literally non-stop to keep their family comfortable and safe.

However, there can be a time when your trusty furnace stops working properly and instead of releasing heat, it blows cold air. This is the last thing you would want to deal with in the middle of a cold, Minnesota winter.

Your favorite heating company in Hugo MN can help you rectify the problem and restore your heat in no time. However, to speed up the process, you need to understand what’s going on.

Here are the most common reasons for your furnace to blow cold air.


If your furnace tends to turn itself on and off frequently, overheating can be the culprit. This is called “short cycling”, which causes your energy bills to rise, makes your furnace less efficient, and is also potentially dangerous, particularly if you’re running a gas-fired unit. There are a number of reasons for your furnace to overheat which include dirty air filters, filthy blower wheel, blocked vents, clogged evaporator coil, or a broken gas valve.

If you have a newer furnace, it’s much safer because it is likely to have a built-in limit switch that powers off the unit when it gets too hot, preventing further damage. Inadequate airflow can also cause your furnace to turn on and off. Dirty filters limit airflow to the heat exchanger, causing it to operate at higher temperatures. It is a good practice to inspect your filters at least once a month and replace them when they are too dirty. This is the simplest thing you can do to keep your furnace in good shape and avoid expensive service calls.

In addition, if you close more than half of your vents or heat registers, you increase the pressure in your air ducts. This slows down your furnace blowers and compromises airflow in the heat exchanger, causing your unit to overheat.

Another reason for your furnace to overheat is a filthy blower wheel. It adds pressure on the furnace, which curbs your unit’s airflow.

Just as overheating is bad for your car, it is equally dangerous to operate an overheating furnace. A qualified HVAC professional can help you identify the problem, fix it, and restore your heat.

Duct Issues

Your furnace produces heated air, which is then circulated throughout your home through the duct network. If there is any leak, a crack or any form of damage anywhere within the ductwork, expect your furnace to blow cold air instead of warm.

These tiny openings will draw cold air that blends with heated air, making your furnace unable to provide comfortable temperatures. Serious damages to the ducts can even result in losing heated air completely.

For this reason, you need to regularly maintain your air ducts. However, the task of tuning up ducts can be too challenging for an average person. The wise thing to do is to have a qualified technician inspect and repair the damage. Also, remember that regular maintenance of your ducts helps preserve them and avoid costly duct repairs in the future.

Electrical Issues

Even if you have a gas-fired unit, your heating system still needs electricity to work. Simple issues such as a tripped breaker inside your electrical panel can cause a number of problems, including your furnace blowing cold air. A tripped circuit breaker can cause your furnace to not turn on at all. It can also lead to a pilot light not turning on.

Most of the time, resetting the circuit breaker fixes the problem. But if the problem remains unresolved, you should call a qualified technician as it could be a sign of a more serious electrical problem.

Stay Safe. Call the Pros

If you’re dealing with a malfunctioning furnace and simple troubleshooting steps don’t quite fix the issue, call Four Seasons Air Specialists. We have teams of trained HVAC professionals who are adept at identifying problems and applying appropriate remedies. We are your dependable Forest Lake heating and air conditioning experts.