5 Ways to Fix a Whistling Furnace

Tired of strange furnace noises?

While a whistling noise isn’t a sign of danger, it does indicate that you have an issue with the blower fan, air leaking from air ducts, low airflow or you have a dirty air filter.

Below you’ll find out how to fix these issues.

Let’s get started.

Why Your Furnace is Whistling

1. Blower fan

Your blower fan or motor may be the culprit of the whistling noise.

The motor’s bearings may wear out over time from age or constant reheating and cooling.

If you have a belt-driven motor, damaged belts can also cause a squealing noise. You can try replacing the belt or realigning them if that’s the case.

2. Air is leaking

The whistling sound from your furnace may be caused by the air escaping somewhere in your air ducts.

An overly powerful fan that’s pushing more air than required can also cause said whistling noise.

Debris in your ducts can also cause a whistling sound, so ensure that the return air vents aren’t blocked off.

If hot air is leaking from your air ducts, then you’re paying more on utility bills. It’s best to get the issue fixed right away to avoid a high bill at the end of the month.

3. Low airflow

The whistling sound from your furnace may be caused by low airflow.

If your blower fan is trying to pull in air but isn’t capable, then it will increase the air pressure inside of your furnace and create a whistling sound.

4. Dirty air filter

As time goes on, your air filter gets dirtier.

If you don’t change it out, then it may start to cause low airflow and create a whistling sound. Change out your air filter and see if that fixes the issue.

5. Bottom of the furnace cover is loose

While it is uncommon, air may be leaking from the bottom of your furnace.

It’s normally a flimsy cover that is screwed in.

You can try pushing the cover up (you’ll need to get on your knees and inspect the bottom of your furnace) while your furnace is working and see if that fixes anything.

Be careful though as it may get hot.

If the whistling noise stops, then you can remove the blower compartment and seal up the flimsy cover.

Try to remove any air leaks that are causing the squeaky noise.

Is a Whistling Furnace Dangerous?

A whistling furnace noise is not inherently dangerous. What you want to worry about is what the sound is indicating.

If the air is leaking, you have low air flow or the blower fan is damaged which means you’ll have costly repairs down the line.

Why Does My Furnace Whistle When Turning On?

The reason your furnace whistles when turning on is from a clogged filter that is reducing the air flow of your furnace.

As air tries to make its way through the dirty filter, it creates a whistling noise that you’re hearing.

When to Call a Professional HVAC Technician?

If you constantly hear furnace noises and are worried about the state of your furnace, you should call an HVAC technician to take a look.

Some sounds may be indicative of grinding parts that will get damaged if no action is taken.

A banging noise is an indication that an explosion is occurring, or from air pressure problems from undersized ductwork.

About Roy Cohen

Roy Cohen has a burning passion for heating, cooling, and ventilation. He aims to help you save money on expensive repairs and bring you the best HVAC products. He has years of experience behind him in HVAC repair and garage maintenance.

You can find Roy at his LinkedIn or his email: [email protected]

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