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Signs Your HVAC Blower Motor Is Damaged

The technical term for the fan that circulates air through a central HVAC system is the blower. The blower is one of the most important parts of the system since it brings air in so the system can cool or heat it and then blows the cool or hot air around the house. As with any other component, the blower can malfunction so that the HVAC doesn’t work effectively or doesn’t work at all. That’s why it’s important to watch out for these signs that can help you know if your blower needs to be repaired or replaced.

Blower Won’t Turn On

The most obvious sign that there is an issue with your blower is that it won’t come on. The blower should normally always start running as soon as your AC condenser turns on. If it doesn’t come on when the condenser starts, you should shut your air conditioning off. The reason is that the AC system will quickly freeze up if the blower isn’t running and bring warm air into the system.

When a gas furnace starts, the blower usually won’t start until the furnace has been on for around 30 seconds. This is because the temperature-limit switch in the furnace doesn’t signal the blower to run until the heat exchanger gets to a certain temperature. If the blower doesn’t end up turning on, the furnace will almost always end up shutting off. This is because the heat exchanger will quickly get so hot that it begins to overheat. That then leads to the temperature-limit switch automatically shutting the furnace off so that it doesn’t suffer any damage.

If your blower won’t turn on, it usually means that either its motor is worn out or the start capacitor is bad. It takes a lot of power for the blower motor to start up, and the start capacitor works by releasing a jolt of electricity to essentially jumpstart the motor. That means that the blower usually won’t be able to turn on if it has a bad start capacitor.

Weak Airflow

Although a blower can sometimes just suddenly stop working, more commonly it will slowly wear out over time to where it doesn’t work as effectively. That means it may start having issues circulating as much air. This in turn leads to the AC cooling more slowly or the furnace or heat pump not putting out as much air. If you notice that your AC or heating system stays on for longer than normal, one thing to check is how much air is blowing out of your vents.

Excessive Noise or Unusual Sounds

You’ll often hear when the blower is beginning to wear out since it will start making more noise and running more loudly than usual. This can also happen because the blower hasn’t been cleaned recently and is clogged with lots of dust. In either case, the motor will end up working harder and producing more noise.

It’s also a good idea to be aware of any unusual noises coming from the indoor part of your HVAC system, such as the air handler where the blower is. Sometimes the blower can start to come loose, leading to it making a rattling sound as it runs. Similarly, you may also hear it make a grinding noise that sounds like metal scraping against metal. This also usually means that the blower is loose and is scraping against the housing as it spins. In some cases, one of the blades on the blower wheel can also get bent and start scraping against the housing.

A howling, screeching or squealing sound coming from the blower is almost always related to the bearings that drive the motor. Most blower motors have sealed bearings that never need to be lubricated, but others have bearings that do need to be lubricated occasionally. That means the sound could mean that you just need to have a technician lubricate the bearings. If you ever hear any of these noises, you should leave your HVAC shut off until a technician inspects it or otherwise the blower motor could burn out. The motor’s bearings can also just wear out over time and either lead to the blower making loud, shrill noises or simply not running. Luckily, the bearings can easily be replaced without needing to replace the blower itself.

If your HVAC system is getting old, it may have a belt-driven blower motor instead of a direct-drive motor with bearings. The belt on this type of motor can also wear or become misaligned. Either issue will lead to it making a loud squealing noise that sounds exactly like when the belt in a car’s engine wears out.

AC Keeps Freezing Up

The evaporator coil in a central air conditioning system can freeze up for a variety of reasons. It will usually start happening if there is a leak in the system that leads to it not having enough refrigerant. More commonly it happens because there isn’t enough warm air being drawn into the system due to a dirty air filter or because the blower isn’t working properly. When everything is as it should be, the blower continually draws lots of air through the evaporator coil. The warm air flowing through the coil prevents all of the condensation that collects on it from freezing. If there isn’t enough warm air flowing through the coil, the condensation can freeze almost immediately because the refrigerant in the cold is so cold.

You’ll know within a short time that your AC is frozen since you’ll end up with warm or hot air blowing out of your vents. Any time this happens, it’s important to turn your AC off or else it can suffer severe damage. After the system is off, you should get it inspected so you know exactly why it’s freezing and can get the issue fixed.

Furnace Keeps Prematurely Shutting Down

As previously mentioned, a furnace will quickly overheat and shut down if the blower doesn’t run. This can also happen if the blower isn’t working effectively and not bringing enough cold air into the furnace. This is another situation where you should shut your HVAC off and get it inspected if you notice your furnace frequently shuts down before it should.

How Regular Maintenance Helps Avoid Blower Issues

The majority of blower issues result from a lack of maintenance, such as failing to have the bearings lubricated or the squirrel cage around the blower cleaned. Having a certified technician maintain your HVAC system twice a year helps to avoid many common issues with the blower and other components. That means your HVAC usually won’t need as many repairs over its life and should last longer. Twice-yearly maintenance will also keep your system working more efficiently so that your cooling and heating costs aren’t as high.

The experienced, NATE-certified technicians at Hoff Heating & AC are ready to expertly handle all of your home’s heating and air conditioning needs. We specialize in HVAC maintenance and repairs and can help if you’re experiencing issues with your blower, air conditioner, furnace, heat pump or mini-split. As a Lennox Premier Dealer, we’re also the best choice for heating and air conditioning installation in O’Fallon and the surrounding areas. To schedule an inspection or any other service, contact us today.