Common Furnace Problems Explained

January 11, 2018

Is your furnace making strange noises? Or have you noticed that your unit is blowing cold air when you’re expecting a comfortable blast of warm air? If so, it could be a signal that your HVAC equipment is about to fail in the middle of this cold winter season. Here are some common warnings that you shouldn’t ignore when it comes to your furnace:

Scraping Sound

If you hear a loud scraping sound that sounds like metal on metal, there is probably something amiss with the blower wheel. If you hear a sound like this, turn off your furnace promptly and call Service Experts Heating & Air Conditioning to inspect the furnace. There are numerous things that could be wrong with the blower wheel. First, it might just be loose and if the piece is not too damaged, can be tightened. Second, it might be that the blower wheel is fractured and will demand replacement. Or third, it might be that the motor mount is what broke, causing the complete blower assembly to shake uncontrollably.

Loud Bang When Furnace Starts

If there is a loud pop when your furnace starts up, there are several things that could be going on. Two regular culprits are a dusty furnace burner or ignitor. A dirty furnace burner or ignitor could prevent the burners from igniting, causing gas to build up. When the gas finally does ignite, it will create the loud bang you hear. This could result in a safety problem, especially if one of these small explosions caused the heat exchanger to crack. Not only could that result in a carbon monoxide leak, but you would end up having to replace the heat exchanger, which could be very pricey.

Expanding and contracting air ducts can also cause loud bangs after the heating system blower starts up. This is a usual annoyance for homeowners with metal ducts. If your furnace is making the loud boom and it is produced by your air ducts, it could be a indicator of undersized ducts, obstructed vents, or a clogged air filter.

Whining Noise

If you hear a high-pitched noise, it could be the shaft bearings are in need of oil, there is an issue with the blower belt, or the blower motor is malfunctioning. A seasonal furnace tune-up will help find these issues before they become substantial problems.

Cold Air Blowing From Heating System

There are a few reasons why your heating equipment could be giving off cold air. It might sound trivial, but the thermostat is the first thing you want to consider. It’s the starting place for any furnace technician, as well. Confirm the system is set to “auto” and not “on.” If the thermostat is set to “on,” your heating system will blow continuously, even when it isn’t heating the air being released, thus blasting cold air. Flipping it to “auto” will make sure the heating equipment only blows when it’s really heating the air.

You should also check your air filters. Typically air filters need to be changed every month to keep them from becoming filthy and clogged. If they aren’t replaced often enough, the clogged air filter may restrict airflow into your furnace. If this occurs, it can overheat your system, causing the system to stop heating as a protectioin.

Your duct work could also be the culprit if it has leaks, connection issues, or was designed incorrectly, which could allow warm air from the heating equipment to leak out. This would not only cause your heating equipment to blow cold air, it could considerably run up your energy bills since your equipment is heating non-living space, and will have to work more to keep your home warm.

There are alternative reasons that your heating system could generate cold air including normal system wear and tear, among others.

If your heating system is exhibiting any of these warning signs, call Service Experts Heating & Air Conditioning at or schedule an appointment online and we’ll send a technician to determine your malfunction and get your home warm and comfortable again in no time.

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