Why is my furnace blower so loud all of a sudden?

Author: Miss Orpha Schultz  |  Last update: Sunday, August 31, 2025

Ineffective belt: A worn-out or defective belt might produce a loud, screeching sound if the blower in your furnace is belt-driven. Airflow restrictions: The blower may have to work harder due to blockages in the ductwork, which will raise the noise level.

Why is my furnace suddenly so loud?

If you're hearing a loud banging or booming noise, this could indicate your furnace has dirty burners. This is hazardous as it can hinder the ignition. This delay in ignition triggers a gas build-up, producing a little explosion when it finally does light. Your burners should be regularly cleaned to avoid this issue.

How to fix a noisy furnace blower?

  • First has it always been noisy?
  • Might not be any trouble or way to quiet it down
  • Try blocking off 1 and of the blower with some card board and duct tape.
  • Install a baffle between the air inlet and the blower
  • Make sure the fan blades are clean
  • Make sure the ac coil is clean
  • See if the air is blocked by closed ducts

Why does my furnace sound like a lawn mower?

If your furnace produces a loud humming or buzzing sound, there could be an issue with the motor. There may also be something wrong with the fan. It can be something as simple as a loose screw, loose door, or improperly installed furnace filter.

Why does my blower motor sound so loud?

the noise you're hearing is more than likely the blower motor brushes hitting the commutator, or the bearing going out. This is a sign that the blower motor itself is going out. The remedy is to get a new blower motor and install it. While you're there, be sure to clean our any debris from the square cage.

Noisy Furnace? - Top 5 Fixes | Repair and Replace

How loud should a furnace blower be?

A low hum is normal while the furnace runs, but if the noise is loud during a cycle or comes on when it wasn't present before, there could be an issue with the fan or capacitor.

How do I lubricate my furnace blower bearings?

You'll probably have to remove an access plate to get at the ports. If the blower has grease cups instead of oil ports, remove the screw caps that cover the cups and fill the cups with bearing lubricant, which is available at automotive and hardware stores. When you lube the motor, you should also check the belts.

When should I worry about my furnace noise?

Loud Bangs, Rumbles, Knocks, or Booms

Loud noises like this are a sign of a build of gas in a furnace. The noise you hear can mean your heat exchanger is at risk of cracking. Even worse, it's a sign that something dangerous could happen if you continue to use your heater.

How much does a furnace blower motor cost?

While costs can vary, homeowners can typically expect the following range: Standard Blower Motors: These might cost between $400-700, excluding labor. Advanced Multi-Speed or Variable-Speed Motors: These are generally more expensive, with costs ranging between $650-1250, not including labor.

Why does my furnace sound like a freight train?

7. Grinding, Scraping, or Clanking. If your furnace sounds like a train grinding and scraping away on tracks, then you probably have an issue with the blower wheel.

Why does my furnace sound like a plane taking off?

If your furnace is making an obnoxious noise, it's likely because the furnace blower motor is turning on and off as part of normal heating furnace cycles. Make sure your thermostat is set properly to the desired temperature and off when you don't need heat (like overnight).

What does a bad furnace fan motor sound like?

Over time, normal wear and tear can cause the furnace motor to start squealing, grinding, buzzing, or whistling sound. Here are some of the most common culprits behind furnace motor noise: Bearings wear out – Bearings allow the blower wheel to spin smoothly.

How do I make my furnace sound quieter?

Here are a few ways to reduce HVAC noise.
  1. Seal Air Leaks. Air leaks are one of the main causes of noise in HVAC systems. ...
  2. Upgrade Your HVAC System. ...
  3. Ventilation. ...
  4. Choosing the Right Location. ...
  5. Insulating the Walls. ...
  6. Cover Your Unit Using Soundproof Materials. ...
  7. Install Flexible Ducts. ...
  8. Get Duct Silencers.

Why is my furnace return so loud?

Restrictive vents or grills: A vent that isn't the right size or shape can make a ton of unwanted noise. Some vents aren't made very well and have very narrow openings for air to enter or have vents that fall closed easily, which means that the HVAC system or furnace has to work super hard to get enough return air.

What does a cracked heat exchanger sound like?

Instead, you should take immediate action and contact an HVAC professional. A cracked heat exchanger can produce different sounds, including popping, banging, whistling, or scraping.

Should you be able to hear your furnace?

On a normal day, your home's furnace might make a little noise as it starts up, when it's turning on, and then when it turns off. You can always expect to hear some noise from the furnace. The thing about this noise is that it should never be disruptive.

What is the life expectancy of a furnace blower motor?

Furnace: A blower motor in a furnace can last a minimum of 10 years but up to 20 if you schedule regular maintenance to keep your unit in good condition. Heat Pump: Like a furnace, a blower motor in a heat pump can last at least 10 years, and up to 15 if the unit undergoes regular maintenance.

Can you replace a furnace blower motor yourself?

Undo the screws on the motor to remove the belly band. The rotation of the motor needs to match the direction of the fans, so position them accordingly. Attach the new motor to the belly band. Center the new motor on the fan wheel, fasten the bolts, and connect the capacitor.

How do I know if my furnace blower motor is bad?

Here are some signs of a broken furnace blower motor:
  1. Loud Operating Noises. When your blower has an issue, you might hear odd noises coming from your vents. ...
  2. Weak or Absent Airflow. Weak airflow or total lack of it is the most obvious sign of a bad blower motor. ...
  3. Overheating. ...
  4. High Energy Bills.

Why is my furnace so loud all of a sudden?

If your furnace suddenly produces loud, sudden banging or booms, you should call an experienced technician as soon as possible. These sounds could indicate stuck ignition, a potentially dangerous situation involving carbon monoxide which is deadly.

How to fix a noisy furnace fan?

Here are ten actions you can take to quiet the noise.
  1. Change Fan Speed Settings. The furnace's fan needs to be calibrated correctly when installed. ...
  2. Fan Alignment. Fan blade alignment. ...
  3. Replace Bearings. ...
  4. Clean Dust Build-Up. ...
  5. Lubricate the Motor. ...
  6. Repair or Replace Mounts. ...
  7. Disconnected Belts. ...
  8. Replace the Motor.

What does a failing furnace sound like?

There are a variety of problems that can cause your furnace to produce loud noises. Types of noises such as scraping, banging, whistling, and popping may be a sign of a loose part, cracked heat exchanger, or dirty gas burners.

Do furnace blower motors have bearings?

One of the more common problems in a blower motor is the bearings. Bearings surround the motor shaft, allowing it to run smoothly at high RPM with almost no friction. When the bearings go bad, the motor may make a grinding or screeching sound, or not run at all because of the friction preventing the motor from turning.

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