Why is my Furnace Making A Loud Noise? What does it mean?

Furnace Tune up – Kennesaw GA

Prior to the start of winter, it’s a very good idea to give your furnace a tune-up. Much like your car getting an oil change, a furnace needs annual care to stay in top working order. If you hear furnace noises give us a call.

A tune-up includes replacing air filters, cleaning air ducts, and checking the battery to ensure that the thermostat control unit is good to go.

What do you do, when you’re winterizing your HVAC unit and you notice that it’s making noises? What do these sounds really mean?

Furnace Noises that Require Attention


Furnaces that make a buzzing noise can mean that the pilot light is not adjusted properly. Too little gas and the pilot light will burn out. Too much gas and it could lead to tiny explosions of built up natural gas in the system.

Other causes of buzzing:

  • The relay switch coming into contact with the control cover
  • Dirty or wore down motor bearings
  • A transformer is about to burn out and die


A Furnace that is humming AFTER it finishes a heating cycle, chances are that the motor is working too hard. Dirt and debris can cause grinding, which wears down the blower motor parts. Manual cleaning by a professional can stop this sound fast and get your furnace back in working order.

Banging or Boom Noises

A loud boom or bang when your furnace starts can be caused by a delayed gas ignition. Delayed ignition happens when gas from an unlit pilot light builds up in the system. It makes a tiny explosion when the pilot light finally manages to catch fire.

This can be caused by:

  • Too much air flow
  • Too little gas being fed to the burner
  • A dirty or blocked pilot light
  • A misaligned burner

Squeaks, Squeals, and Scraping Sounds

When a furnace is squeaking or squealing while running, chances are that the fan belt needs to be replaced. It could also be that the bearings in the blower motor need lubrication or the blower motor needs to be repaired.

Scraping sounds can be caused by loose blower motor wheels rubbing against the blower casing. Another cause can be when the motor mount breaks and the entire assembly is hitting the housing.

Furnace Repair or Maintenance – D McKeon Heating and Air

Anytime your furnace is making a strange noise listed above or a noise that is not familiar to you it is concerning.  These noises are a signal from your furnace that it’s time to call a professional for help. Don’t try to ignore the issue as it not only can be dangerous but it can cause other issues in the future.

Service technicians at D MCKeon Heating and Air in Kennesaw, GA can help you fix all of these problems, and get your furnace in tip-top shape for winter.