What are the causes of Furnace Problems?

Many homeowners turn on their furnaces every fall to get ready for winter. However, sometimes furnaces have problems that lead to a need for furnace repair or replacement. In this article, we will outline the most common causes of furnace problems so you can be prepared and know what to do if your furnace malfunctions during the cold weather season.

Cause #1: Lack of Regular Maintenance

One cause of furnace problems is lack of regular maintenance. Often, homeowners only think about their furnaces during the winter and then all focus is on keeping them working until spring. Remember that your furnace works hard to heat your home all year long, not just during the winter months. Scheduling a yearly service for your furnace in the spring and fall will help you avoid many common causes of furnace problems.

Cause #2: Old Furnace Systems

Another cause of furnace problems is an old furnace system that isn’t running at peak efficiency. To keep your home warm during winter, furnaces need to be up-to-date and running efficiently. If you have an old furnace that is 15 or more years old, it might be time to consider new furnace installation.

Cause #3: Dirty Air Filter

One of the most common causes of furnace problems is a dirty air filter. A dirty air filter restricts airflow and prevents your furnace from running at peak efficiency – resulting in your furnace having to work harder and longer, leading to malfunctions. Check and change the filter at least once a month, or more if you have pets or live in a dusty area.

Cause #4: Low Temperatures Indoor

When the indoor temperature of your home is too low, this can lead to problems with your furnace. Make sure your home is at least 65 degrees F to keep the furnace from shutting off.

Cause #5: Broken Furnace System Components

A broken furnace system component can cause many different problems, such as low airflow and restricted water flow. When components of your furnace break, they need to be repaired or replaced right away before all of the furnace components fail to cause a complete breakdown.

Cause #6: Unusual Noises

Another common cause of furnace problems is unusual noises coming from your unit while it is running. If you hear strange or new sounds, it may be an indication that something on the furnace system is broken, which can lead to poor performance and other more severe problems. Remember, if you hear a new noise, turn your furnace off immediately and have an HVAC professional inspect your furnace.

Cause #7: Worn Out Motor Belt

Belts that are worn out can cause problems with the furnaces motor. Without a properly working belt, the motor will not spin. This causes even more damage to the motor and surrounding components, leading to complete breakdown.

Cause #8: Ductwork Leakages

A broken duct or a dirty filter combined with a dirty furnace can cause your unit not to heat properly. A common sign of a problem is that the air coming from the registers seems cooler than usual. This occurs when there is extra airflow coming into the unit. Look for signs of loose sheet metal and insulation around the ducts, and be sure to keep your filters clean so your heating and cooling systems can operate at peak efficiency

Cause #9: Blower Motor Malfunction

A blower motor malfunction affects airflow through the furnace, resulting in poor temperature control. When a blower motor malfunctions, it is usually due to a broken blower motor or capacitor. You can fix this problem by replacing the blower motor or having the blower motor and capacitor replaced altogether.

Cause #10: Dirty Furnace Coils

Dirty furnace coils cause your furnace to work harder than normal and drastically reduce the life of your furnace. A dirty furnace coil reduces energy efficiency and will eventually lead to the need for new furnace installation.

When you are aware of these common causes of furnace problems, you can be prepared in case your heating system goes out during the cold winter months. If your furnace stops working or seems to run poorly, turn it off immediately and contact an HVAC professional to come out and inspect your unit.

How do you prevent furnace problems?

Furnace tune-up and maintenance:  Keeping up with semi-annual furnace tune-ups can help prevent your furnace from breaking down. Having a professional inspect and clean the components of your system such as the coils, motor and blower will keep your unit running at peak performance and make it less likely to need furnace repairs or replacement soon.

Furnace filter change:  Replacing your furnace filter regularly can help keep your heating system running at peak performance. A clean filter also helps reduce the load on your heating system, which means a longer life span for your furnace and ultimately higher savings in energy costs.

Winterize your home:  Taking the time to winterize your home can help prevent furnace problems in the future. Winterizing your home is a short project that should only take about 2 hours of your time and will save you money by preventing furnace problems like frozen pipes and poor indoor air quality.

Cleaning and sealing ducts:  If you have dirty or leaky ducts, your furnace will work harder than it needs to. Cleaning and sealing the vents in your home can help increase the life of your heating system and reduce energy costs by allowing for better airflow.

When should you get your furnace inspected?

Furnace inspections should be done at least once a year or more depending on how much you use your heating system and whether there have been major changes to it such as the installation of a humidifier, dehumidifier, or other devices that may affect the performance of your furnace.

Furnace inspections are especially important if you find that your system is not working properly or if it has broken down completely. The inspection will reveal any problems with the unit and help HVAC professionals give you an accurate estimate for repair costs if needed.


As you can see, furnace problems are common and there are several ways to prevent them. To get the most out of your heating system, it is important to be aware of these 10 causes of furnace problems so you know what preventive measures you can take to extend the life of your unit. With proper maintenance and care, your heating system can be running like new for many years.