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Why Is My Furnace Making Noises?

technician maintaining a furnace

Some light crackling at the end of a heating cycle or humming when your furnace is on are normal noises that shouldn’t cause too much concern. However, other sounds from your heating system can indicate serious underlying problems that need immediate attention. It’s important to know the difference and when it may be time to call in a professional for furnace repair.

The HVAC experts at AAA Heating & Air Conditioning can help you determine what certain sounds mean for your system and when it may be time to contact our team for emergency furnace repair.

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1. Gurgling Noises

It may seem strange to hear gurgling or bubbling noises from your furnace, but it’s more common than one might think.

In newer, high-efficiency systems, exhaust fumes are vented from the unit but can produce condensation from moisture in the air.

If your furnace struggles to drain this condensation properly, it can cause gurgling, dripping, or bubbling sounds.

The Fix

In most cases, gurgling noises can be fixed by unclogging the drain pan or removing blockages from the drainpipe.

2. Whistling Sounds

One of the most common furnace noises is a high-pitched whistling, squealing, or screeching. There are several reasons why your furnace may begin whistling, including:

  • A blockage or air leak in your ductwork
  • A partially closed air vent
  • Increased air pressure escaping through gaps in your vents
  • A clogged air filter

The Fix

Inspect your furnace carefully to pinpoint where the sound is coming from:

  • If it’s coming from your intake or exhaust vents, clear away any obstructions and ensure they’re open.
  • If you have clogged or leaky ductwork, you may need duct cleaning or sealing.
  • If you have a dirty air filter, replace it now and change it every three months to prevent whistling sounds from happening again.

3. Rattling Noises

Rattling, buzzing, or humming noises are often associated with loose or unsecured components within your furnace. Loose screws, bolts, and other parts can create a rattling sound during operation.

In severe cases, rattling noises in your furnace may even indicate an issue with your heat exchanger, leading to carbon monoxide buildup in your home.

The Fix

If you suspect parts have become loose within your system, turn off your furnace and call a trusted HVAC technician. They’ll take care of the issue and restore your system to full functionality.

4. Popping Sounds

Popping noises are common in furnaces and are even considered fairly normal — especially when the system first turns on. This is usually not cause for concern and is often attributed to the metal’s natural expansion and contraction as your system heats up.

However, if popping becomes too loud or frequent, it could indicate a serious issue, such as a dirty burner delaying ignition. If it’s not addressed, this problem could crack the heat exchanger and compromise your home’s safety and comfort.

The Fix

If you hear persistent popping noises, book a furnace repair to ensure your burners are clean and the ignition system is intact.

5. Banging Noises

Loud banging or booming noises can be alarming and may indicate a serious problem within your furnace. The most common reasons for banging noises include:

  • A malfunctioning ignition system
  • A damaged blower wheel
  • A cracked heat exchanger

The Fix

Loud banging noises often indicate a serious component issue, so hire an HVAC team to inspect your heating system and identify the source of the sound. Unfortunately, a cracked heat exchanger often means a furnace replacement.

6. Clicking Sounds

When a furnace starts up or shuts down, some clicking noises may occur, which are completely normal.

However, if the noise persists or is irregular, it could indicate an issue with the ignition system, such as:

  • Dirty burners
  • A malfunctioning ignition board or valve
  • Damaged flame sensors

In addition to ignition system problems, persistent clicking noises can sometimes indicate a problem with your compressor.

The Fix

The best way to resolve persistent clicking noises in your furnace is by having a professional inspect and repair your system.

7. Scraping Noises

If you hear scraping noises like metal rubbing against metal, there could be a problem with your furnace’s blower wheel.

Blower wheels that are broken or loose can produce a loud noise that can be alarming.

The Fix

Shut down your furnace immediately if you hear scraping sounds, and contact a skilled technician to diagnose and repair the problem.

Contact AAA Heating & Air Conditioning for Furnace Repair in King & Pierce County

Does your furnace make strange noises or smell bad? AAA Heating & Air Conditioning is here to help. Our highly trained HVAC team services all brands of gas, electric, and propane furnaces, so we’re ready to act at the first sign of needed service. We’ll deliver the prompt, professional response you need to keep your unit running reliably.

Request furnace repair in the Puget Sound area by calling our team at (253) 234-1278 today!

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Proudly Serving

Kent, WA and the surrounding areas

Kent | Auburn | Renton | Maple Valley | Ravensdale
| Covington | Black Diamond | Federal Way | Seattle
| Des Moines | Burien | SeaTac | Normandy Park |
Issaquah | Newcastle

View More