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What Causes a Furnace to Make a Grinding Noise?

What Causes a Furnace to Make a Grinding Noise?


Is your furnace grinding away every time it runs? If so, you're not alone. Many homeowners experience this loud, unsettling noise. What’s the reason behind a furnace making a grinding noise, and how can you fix it? A Perfect Climate Heating & Cooling explains the common causes of grinding sounds from furnaces and what you need to do to stop these sounds.

Why Is My Furnace Making a Grinding Noise?

Typically, grinding sounds from a furnace have to do with issues impacting the blower assembly. The blower motor and fan are responsible for moving air through the furnace and home. The most common causes behind loud grinding noises coming from your furnace are as follows:

Blower Wheel Issues

If your furnace is making a grinding noise, it could be due to a detached blower wheel. If the wheel within the blower assembly becomes detached, it can cause the furnace to make loud grinding furnace noises as the wheel grinds against other components in the vicinity.

If you think your furnace may have a detached blower wheel, turn the furnace off to prevent any further damage. It's important to call a furnace repair specialist to diagnose the problem and make the necessary repairs. Left unchecked, a detached blower wheel can cause serious damage to your furnace and may even lead to a fire.

Loose Motor Mount

Another possible reason your furnace is making a grinding noise is that the blower motor mount has become dislodged. The blower motor is what powers the blower fan, and the mount helps to keep it in place. If the mount is loose or damaged, it can cause the motor to vibrate, which in turn can create a grinding noise.

To fix this problem, you'll need to replace the mount. Turn off the furnace and call a licensed HVAC technician to make the repair. Once the new mount is in place, your furnace should run more smoothly and quietly.

Bad Motor Bearings

If your furnace starts making grinding noises, it could be a sign that the blower motor bearings are bad or unlubricated. The bearings keep the motor running smoothly and require some regular maintenance. If the bearings are worn out or dirty, they can cause the motor to overheat and you’ll hear the furnace making a grinding noise. In some cases, the bearings may also seize up, causing the furnace to overheat and shut down.

Preventative maintenance tune ups help prevent issues with the blower motor bearings. One important step of this service is lubricating the bearings so the motor can operate without excessive friction.

If you suspect that your heating system is making loud noises due to bad or unlubricated blower motor bearings, it's important to call a furnace repair technician for diagnostic and repair assistance. A tune up may be recommended to lubricate dry bearings, or bearings may need to be replaced. Bad bearings can damage the motor, so it may be possible that the motor itself requires replacement.

Loose or Broken Parts

When there is a furnace or heat pump making a grinding noise, the sound can be due to a loose or broken component. Bolts or other parts may work their way loose and fall into the blower, which will cause a furnace noise as these parts beat up against the blower wheel as it operates.

While this can be frustrating, the good news is that it may be an easy fix. Turn off the furnace, open the blower access panel, and check inside the blower for loose parts. Remove any parts you find loose in the blower assembly. Reinstall the part in its correct position if it is not damaged. In most cases, the issue can be resolved by simply replacing the broken part. However, if you cannot identify the part or don’t know where it came from, call in a professional for help.

Contact A Perfect Climate Heating & Cooling for Furnace Repairs in Indianapolis

If your furnace is making a grinding noise, there are several potential causes. We’ve outlined the most common ones in this blog post so you have a better idea what you’re dealing with.

It’s best to contact a professional technician to diagnose and fix the problem for you. Don’t wait to address the grinding noises from your furnace, as more damage can be caused in the meantime. Call us today for furnace repair services and get back to enjoying comfortable indoor temperatures without disruptive sounds!


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