Causes and solutions for a furnace making a buzzing noise.

Furnace Making a Buzzing Noise? 4 Causes and Solutions

Is your furnace hissing like a cornered diamondback snake? Is it making odd sounds at night that have you questioning whether ghosts are real? Fear not — the solution may be simpler than you think. Before you organize a seance, let’s explore common causes and solutions to your noisy furnace problems.

4 Reasons Why Your Furnace Might Be Buzzing

There are four common reasons your furnace is making buzzing noises:

1. Your transformer box is malfunctioning

Humming and vibrations could indicate your transformer box is loose or the transformer is malfunctioning. The transformer helps to increase or decrease the flow of electricity to your furnace to meet system needs. If left unrepaired, it can lead to tripped breakers and heating failure.

2. Your capacitor is broken 

A low humming noise when your furnace turns on could signal an issue with your capacitor. The capacitor sends energy to the furnace fan motor. A faulty capacitor can cause the fan to run slower, run hot, or start and stop unpredictably. 

3. Your blower motor isn’t performing properly

A decrease in airflow is often a sign your blower motor isn’t performing properly. As the blower motor function becomes weaker, the furnace works harder to compensate for the weak airflow and you might hear a loud buzzing from the furnace. You’ll also experience overheating and higher energy bills.

4. Your air ducts are loose

If your air ducts are loose, you’ll hear a buzzing or rattling noise when the furnace turns on and whistling sounds coming out of the vents. You may also experience more dust in your house as the gaps from the broken seals draw in particulates from around the furnace and force them through the venting system. 

What Other Noises Coming from Your Furnace Might Mean

It isn’t always easy to distinguish one furnace’s noise from the next, but any sound that’s out of the ordinary is worth paying attention to. Listen for any of these noises before assuming a source, and contact a furnace repair pro to properly diagnose and solve any issues.

Banging noises

A loud banging noise as the furnace turns on is probably an issue with the ignition system. If it happens after the heat starts blowing, the sound is probably the metal ductwork heating and expanding. Insulating the ductwork could lessen the banging caused by the temperature change. It can also minimize energy loss and lead to lower heating bills.

Humming sounds

Humming sounds can result from several furnace issues, including a clogged air filter or an unlubricated blower box. Listen for companion sounds, and note how long the humming persists and when the sound is loudest. Also note any other signs like weak airflow, tripped circuit breakers, or grinding noises, and contact your local HVAC pros for service if they’re present.

Clicking noises

Repeat clicking noises and a cold furnace may occur when you have a faulty ignitor or gas valve, and blower bearings can cause clicking noises when they’re caked with dust and debris. Because they are rolling, the sound will be at steady intervals as the damaged sections circle, like a rock stuck in a tire tread. 

A loose or dirty draft inducer fan can also make a clicking noise. The furnace will run normally, but as the blades in the inducer fan wear down, you’ll hear a clicking noise as it cycles. 

Squealing or screeching

The two most common culprits of squealing or screeching are your belts and bearings. A frayed blower belt or loose fan belt can slip, pull, and catch along the wheel, leading to squealing noises. This may heat the belt and give off a rubbery, burning smell. 

Worn down and dirty blower motor bearings can cause a squealing, grinding, or screeching noise. 

Rattling noises

The most common cause of a rattling furnace noise is loose bolts. It can happen after a recent repair or installation if the bolts aren’t properly tightened. It can also happen over time as temperature changes cause expansion and contraction of the metal, loosening the bolts.

Rattling noises can also mean something is stuck in your vent — like your kid’s Lego pieces or a kitchen utensil.

How To Stop Your Furnace From Buzzing

A furnace making a buzzing noise is disruptive, and it signals a potential breakdown is on the horizon. If the noise is coming from the ducts, close any gaps and secure loose connections with a mastic sealant, fiberglass mesh, or aluminum tape. Replace any damaged duct sections.

If these solutions make little to no impact on the furnace’s buzzing sound, it’s time to call in a heating repair professional

When Should You Worry About Your Furnace Making Noise?

Furnaces make noise when they run. It is only cause for concern when your furnace starts making new noises, which often signal the start of a problem. It’s also common for an aging furnace to experience more than one issue at a time, so you might be hearing sounds of several issues.

Regular maintenance helps keep your furnace running smoothly, leads to cleaner air, and prolongs the life of your furnace. Preventive furnace maintenance is best performed in the fall, before the cold Panhandle winter sets in.

Frank’s Knows Furnace Noises

From a buzzing transformer box to grinding bearings, Frank’s Repair Plumbing knows furnace noises. We have experienced and trustworthy heating service technicians who know the difference between a squeal, a squeak, and a hum and what each questionable noise means to the health of your furnace. 

Contact us for reliable service in Amarillo, Pampa, Canyon, Bushland, Dumas, Borger, Fritch, Panhandle, and White Deer areas. With over 70 years of providing reliable HVAC services during unpredictable Texas Panhandle winters, we know furnaces. We can take care of that pesky noise that’s causing concern — and improve your system’s efficiency to lower your heating bills.