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Carrier Furnace Grinding Noise – How To Fix It?

Carrier Furnace Grinding Noise – How To Fix It?

Furnaces are vital for maintaining a comfortable home environment, especially in the frigid winter months. They provide warmth when it’s freezing outside and circulate cool air in the scorching summer. However, it can be disconcerting when your furnace begins making strange and disturbing noises. In this article, we will delve into the common culprits behind these disruptive furnace sounds and offer solutions to rectify them. Furthermore, we will emphasize the significance of regular maintenance in ensuring the longevity of your Carrier furnace.

Identifying The Source Of Carrier Furnace Noise

Unusual noises from a Carrier furnace typically stem from the grinding or friction of metal components. Let’s explore the primary causes of these noises and how to address them:

1. Loose Screws and Dirt on the Blower Wheel

The blower wheel is a critical component of your furnace, linked to the blower motor shaft via a set screw. When this screw becomes loose, the blower wheel may wobble and create grinding sounds. Accumulated dirt and debris can also strain the motor, resulting in unpleasant noises.

To tackle these issues, follow these steps:

  • Turn off the power to the furnace for safety during maintenance.
  • Examine the blower wheel for visible damage or signs of wear. Depending on your furnace model, the replacement procedure may vary.
  • Remove the unit door but avoid disconnecting any wires from the blower.
  • Unscrew the blower wheel from the motor shaft, granting access to the internal components.
  • Use a small brush to clean the fan blades, motor housing, and the squirrel cage. Finish by vacuuming the blower cabinet to remove any dirt and debris buildup.

2. Lubricating the Blower Motor

Carrier Furnace Grinding Noise – How To Fix It?

Furnaces typically come with two drive systems: direct-drive and belt-drive motors. Direct-drive motors usually have sealed bearings and do not require lubrication. Conversely, belt-drive fans necessitate regular lubrication to ensure smooth operation.

To lubricate a belt-drive blower motor, follow these steps:

  • Locate the access panel behind the gravity panel (if applicable) and unscrew it counterclockwise.
  • Check for oil ports on the motor, often indicated by colored plastic caps, typically red, positioned vertically on both sides.
  • Remove these caps and apply a small amount of bearing oil to each oil port. Avoid overfilling to prevent leakage. Reattach the caps and secure the access panel.

If lubrication does not resolve the issue, consider replacing the blower motor with a new one.

3. Draft Inducer Motor Bearing Replacement

The draft inducer motor is pivotal for maintaining proper oxygen flow to the furnace’s burners. Over time, the bearings within this motor can wear out, leading to increased noise levels. In such cases, it is advisable to replace the draft inducer motor.

Follow these steps for draft inducer motor replacement:

  • Turn off the gas supply and power to the furnace for safety.
  • Remove the furnace panel and set it aside.
  • Locate the draft inducer in the upper-left part of the furnace chamber and unplug the Molex connector.
  • Utilize a screwdriver to remove the screws securing the shield plate to the draft inducer. Then remove the three mounting bolts with a 1/4-inch socket.
  • Next, remove the round clip from the cooling fan using a flathead screwdriver, then detach the fan from the driveshaft.
  • Loosen the set screw securing the blower fan to the driveshaft with a hex wrench and remove the blower fan from the driveshaft.
  • Flip the assembly and remove the three bolts securing the motor bracket and the motor bracket itself.
  • Using a 1/4-inch socket, remove the two bolts connecting the motor to the motor plate and then remove the motor bracket.

During installation, ensure proper alignment of the set screw with the flat edge of the driveshaft when attaching the blower fan to the new motor.

Maintaining Your Carrier Furnace

Proper maintenance of your Carrier furnace is vital for its longevity and efficient operation. Here are key maintenance tasks to consider:

1. Regularly Clean and Replace the Filter

The furnace filter, typically situated where the return duct enters the furnace, removes particles from the air before it enters the furnace. A clean filter can last several months, depending on its quality. Regularly changing or cleaning the filter enhances indoor air quality and furnace efficiency.

2. Check the Blower Motor

The blower motor is crucial for your furnace’s proper operation, circulating warm air from the heat exchanger and assisting in cooling. Periodically inspect the blower motor to ensure smooth and quiet operation. Unusual noises may indicate underlying issues requiring attention.

3. Clean Vents and Ductwork

Dirt and debris can accumulate in vents and ductwork over time, affecting your furnace’s heating and cooling efficiency. Routinely clean vents and ducts or consider professional maintenance to ensure optimal airflow.

4. Proper Placement

Position your furnace away from flammable materials like gasoline, paint, fabrics, and paper boxes to prevent fire hazards. Blocked exhaust flues can also lead to health issues due to the release of harmful gases such as carbon monoxide, nitrogen dioxide, and sulfur dioxide.

Other Furnace Noises

In addition to grinding noises, there are other furnace sounds to be aware of, as they can indicate various issues:

  • Humming Noise
  • Banging Noise
  • Shrieking Noise
  • Popping Noise
  • Scraping Noise
  • Rattling Noise

When to Replace Your Furnace

Carrier Furnace Grinding Noise – How To Fix It?

Furnaces have an average lifespan of 15 to 20 years with proper maintenance. However, there may come a time when replacement is the best course of action. Consider replacing your furnace if you experience any of the following:

  • Frequent and costly repair bills
  • Inconsistent temperature control
  • The thermostat’s temperature settings change on their own
  • The furnace blows cold air
  • Noise levels continue to increase over time
  • Uncontrolled escalation of energy bills

Cost of Replacing a Furnace Blower Motor

Replacing a furnace blower motor can cost between $400 and $600. Single-speed blower motors usually cost around $450, while variable-speed motors may be priced higher, often exceeding $600.

The Average Lifespan of Furnaces

Carrier Furnace Grinding Noise – How To Fix It?

On average, Carrier furnaces can last between 15 to 20 years with regular maintenance, including motor replacements and thorough cleaning.


A noisy furnace can be a significant source of discomfort and concern, especially when it should be providing comfort in your home. However, with a better understanding of the potential issues causing these noises and the solutions provided in this article, you can enjoy a quieter and more efficient furnace after addressing the underlying problems. By following proper maintenance practices and being vigilant about the signs of furnace trouble, you can ensure a more pleasant heating and cooling experience in your home.

Carrier Furnace Grinding Noise – How To Fix It?

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