Facts On Why Is My Furnace Making A Loud Vibrating Noise?

In this blog post, we will study in detail the reason behind the loud vibrating noise made by the furnace.

Why Is My Furnace Making A Loud Vibrating Noise?

Weird noises coming from your furnace such as clicking, buzzing, humming, crackling, rattling, or banging may be due to the low airflow and dirty air filters.

Common Causes of Loud Vibrating Noise in Furnaces

Your furnace might be humming or buzzing. This could mean various issues with your heating system

  • Loose Components and Screws
  • Issues with the Blower Motor
  • Problems with the Heat Exchanger
  • Faulty Bearings or Belt
  • Dirty or Blocked Air Filter
  • Low Airflow in Ducts or Vents
  • Combustion Leak or Expansion
  • Ignition or Transformer Issues

For example, 

It could be loose components, a malfunctioning blower motor, clogged air filters, or low airflow through the ducts.

Loose Components and Screws

Strange sounds from your furnace are caused due to the loose components and screws. Rattling, banging, and clicking are all potential noises. 

Here’s 6 things to consider:

  1. Loose screws can lead to vibrations and rattling.
  2. Loose ductwork connections can cause humming.
  3. Loose panels can vibrate and rattle.
  4. A loose blower motor fan can squeal.
  5. A dirty or damaged blower wheel can cause loud noises.
  6. The heat exchanger can pop or crack if loose.

Issues with the Blower Motor

As a homeowner, strange noises from your furnace can be concerning. The blower motor is responsible for circulating warm air throughout your home and ensuring proper airflow. 

If you hear buzzing, humming, clicking, cracking, squealing, or rattling coming from your furnace, it could be an issue with the capacitor, transformer, belt, bearings, or other components in the system.

Problems with the Heat Exchanger

The heat exchanger is a key part of your furnace. It is responsible for transferring heat from the combustion process to your house’s air supply.

If not maintained, it can cause problems. Signs include 

  • Louder clicking
  • Buzzing
  • Reduced airflow
  • Weak warm air
  • Strange smells

Ignore these issues for too long and you could damage other parts of your heating system. This could even be dangerous if there is leakage or combustion gasses escape. 

Faulty Bearings or Belt

Is your furnace making odd noises? It could be faulty bearings or a belt. 

Let’s break it down:

Rattling, banging, or hummingBlame faulty bearings.
Rattling, banging or hummingBlame a loose or frayed belt.

Dirty or Blocked Air Filter

A blocked air filter can cause low airflow and strange noises. It restricts airflow to your home, reducing heating efficiency and causing a buzzing sound or rattling from the system. The furnace blower has to work harder, meaning reduced airflow.

Overheating of the heat exchanger due to inadequate airflow can be dangerous. The metal parts expand and contract, causing cracking and even breakage which may result in a combustion leak.

To avoid this, clean or replace air filters at least every 3 months. Dirty filters cause wear and tear on the fan motor and other components.

Low Airflow in Ducts or Vents

It could be a combustion leak, or your home expanding like a balloon. Low airflow in ducts and vents can cause these noises. It’s a sign of a problem that needs professional attention.

A clogged air filter is often the culprit. This restricts airflow and makes the blower motor work harder, causing vibrations and humming. 

Loose components in the furnace can also vibrate, creating an irritating noise.

To prevent low airflow issues, it’s important to schedule regular maintenance. HVAC technicians can clean and inspect the unit. 

Removing dirt from filters and ducts improves airflow and efficiency.

Another cause is a malfunctioning blower motor belt. If the belt is worn or attached incorrectly, weak airflow can result in buzzing or even cracking sounds.

Causes Of Combustion Leak or Expansion

If you hear a loud vibrating noise from your furnace, it could be due to either a combustion leak or expansion. 

Let’s look closer at the main causes.

Combustion LeakThis is when there is a crack in the heat exchanger. It can cause carbon monoxide leaks, which can be hazardous.
ExpansionHigh temperatures can make metal components of the furnace such as ductwork and panels expand, creating a noise like expanding metal
CauseImproper installations or shifts in temperature can be the cause.
SignsSigns of combustion leaks are cracks on the heat exchanger or rusty metal parts with white grainy residue. Expansion noises occur when the heating system turns on and off unexpectedly.
SolutionCombustion Leaks should be fixed by professionals. Expansion problems can be solved by tightening screws, nuts, and bolts. An infrared camera may detect hot spots that signify possible arcing/expanding issues.

Ignition or Transformer Issues

A buzzing sound coming from your furnace could indicate an issue with either the ignition system or the transformer

If it’s a continuous buzzing noise, it could be an issue with the combustion chamber. Whereas, a clicking noise could mean a problem with the transformer. 

Don’t neglect regular inspections by professionals as regular maintenance and repairs can help prevent future issues with the ignition and transformers.

Professional Help for Furnace Repair Services

Best to call a professional to check it out. Ignoring it will lead to bigger repair costs. They’ll also check for cracks, leaks, combustion, and ventilation problems.

A technician will inspect your heating system for any signs of trouble. Like capacitors, transformers, and ignition systems. 


In conclusion, regular maintenance and inspection by an HVAC technician should be conducted for the better working of furnace systems.