December 6, 2018 FurnacesInfo Articles

There are a lot of heating options available out there, but the furnace remains the most popular. A furnace has the ability to condition and filter the air effectively, giving you the comfort and safety you need during a cold night. But not every time your system will run perfectly fine. There are times when it can blow cold air instead of warm.

Marsh Heating and Air Conditioning is a leading heating company in Champlin MN that offers professional furnace repair services. We can help you identify the problem, fix it, and restore your heat in no time.

Some of the most common reasons for an underperforming furnace may include:


When a furnace overheats, it turns itself on and off frequently. This issue is called “short cycling”, which is a primary cause of high fuel consumption and furnace failure. A dirty filter can cause your furnace to restrict the airflow within the heat exchanger, causing it to work harder than it should. Checking and replacing the furnace filter periodically can help avoid this problem. This is one of the simplest things you can do to keep your furnace running smoothly. Do not ignore this problem as repeated overheating can damage the heat exchanger, which is a costly part to repair or replace.

Closed registers can also cause your system to overheat by increasing the pressure in your air ducts. This slows down your furnace blowers and decreases the airflow within the system.

In addition, a clogged evaporator coil, a dirty blower wheel, or a broken gas valve can also contribute to the overheating of your furnace.

The best step to take is to have your furnace checked by a qualified professional, who can identify the cause of the problem and rectify it to avoid having more serious problems.

Thermostat Issues

Besides overheating, a key reason for a furnace to blow cold air is a problem with the thermostat. This device controls your heating system that determines when and how much heat will be produced by the furnace. Ruling out the possibility of the thermostat being set to ON instead of AUTO, there are still a couple of reasons for it to malfunction.

If your thermostat has old or faulty wiring, accumulation of dust, extreme temperature changes and similar issues, it can cause your furnace to not work properly.

Simple steps like changing the battery can fix the problem. Weak or dead batteries are the main cause of thermostat malfunction. Also, loose electrical connections, faulty, or aging wiring can result in thermostat issues, leaving you in the cold.

Ductwork Leakage

Identifying the problem with ductwork can be a challenging task. Having said that, when a furnace is blowing cold air, it could mean that there is either a leak or other problems within the ducts. If there are cracks or even small openings in your ducts, they may take in cool air that mixes with heated air. If there is a major damage to the ductwork, you may lose heated air altogether.

Though oftentimes neglected, your ducts are an important part of your HVAC system. You should keep them working properly by regular professional maintenance.

Electrical Problems

Regardless of the type of system you have, it still requires electricity. Simple factors like a tripped circuit breaker inside your electrical panel can cause a number of issues, including a furnace that blows cold air. In fact, a tripped breaker results in a furnace that won’t even turn on at all. It can also affect your pilot light, causing the furnace to not start.

When too many appliances are running at the same time, the system may be overloaded, which can cause your circuit breaker to trip. Moreover, faulty wiring, damage wiring or grounding faults can also contribute to this problem.

For your own safety, if resetting the circuit breaker doesn’t solve the problem, do not try to straighten out the issue on your own, especially if you are not trained. Contact a local HVAC professional who can determine the root cause of the problem and fix it for you.

Heating Problems? Call the Experts

The last thing you’d want is a furnace that blows cold air on a rather chilly night. Call Marsh Heating and Air Conditioning to solve your problem and restore the comfort and safety of your home. We are your trusted Blaine furnace repair contractor serving you for more than 40 years.