Why is my Air Conditioner Making Whistling Noise?

Do you hear a whistling noise whenever you turn on your air conditioner? Don’t fret – before you consider an AC replacement, remember that noise is not always a result of serious damage. In most cases, a whistling noise from your air conditioner is a warning sign of impending damage. It usually calls for your urgent attention and possibly a professional check.

Although many homeowners understand the internal workings of their AC, the outdoor unit can be a different story. Read on to find out why your air conditioner is making a whistling noise and what steps you should take if repairs are necessary.

What causes air conditioning whistling noise?

Airflow issues are one of the main sources of air conditioning whistling noise. This usually occurs when a clogged vent or blockage reduces the blower’s air volume, causing your air conditioner to work harder and faster to push airflow in a high-pitched whistling noise.

If left unchecked, insufficient airflow can harm your system and increase your energy bills. As a result, you’ll want to address whatever is causing the air conditioning whistling noise as soon as possible.

Thankfully, some airflow issues are simple to diagnose and repair without the assistance of an expert, so let’s consider some causes of air conditioning whistling noise that can be fixed using DIY methods.

4 Airflow Problems That Cause Air Conditioning Whistling Noise

1.       Dirty Air Filters

Air filters are designed to remove unwanted particles from your home. Still, when it becomes clogged, it restricts airflow and causes overheating, resulting in your air conditioner making a whistling sound.

Simply replace your dirty air filter to resolve this issue. Ideally, you should replace your air filter every three months to keep your cooling system in perfect working condition.

2.       Blocked Air Vents

If your air conditioning unit is making a whistling noise inside your home, it is most likely due to clogged supply vents. The supply vent is positioned inside the house along the corridor and aids in air passage into the air conditioning system. If something gets in the way of the vent, it interferes with the duct’s ability to work properly.

To resolve this issue, clear the vent grills of dust and remove any obstructions, and always keep the vent open.

3.       Closed Damper

Dampers are metal levers positioned in the ductwork that you can close to restrict airflow from being delivered to specific areas of your home, particularly rooms that are not in use. While cleaning, a damper can become closed. When this happens, airflow is restricted, resulting in a whistling air conditioner.

Ensure that all of your home’s dampers are aligned with the ducting. Also, make certain that all dampers are open, except those in guest rooms and other vacant rooms.

4.       Too Many Closed Doors

During the winter, you may be inclined to close as many doors as possible to maintain a warm environment. But keeping too many doors closed could be the source of your air conditioner’s whistling. It narrows down the channel of air movement in your home to only a tiny region beneath the door, causing airflow restriction in your AC unit and making the blower work harder to extract the air.

You should keep your doors open as much as possible to allow for better and more consistent air movement.

These airflow problems are just a few of the numerous causes of air conditioning whistling noise. If the whistling noise persists after addressing the issues, you may be dealing with a more serious problem that needs the assistance of an HVAC professional.

Causes of Air Conditioning Whistling Noise That Needs A Professional To Fix

Refrigerant Leak

Another reason your air conditioner makes a whistling noise could be a refrigerant leak. If a hole in your refrigerant lines or an internal valve allows air to escape, your AC unit produces a whistling or hissing sound. If left uncontrolled, a refrigerant leak could lead to more serious cooling system damage.

When you hear a whistling noise from your air conditioner, check to determine if there is a refrigerant leak. If this is the case, turn off your air conditioner and contact an HVAC professional as soon as possible for an AC repair.

Leak in the Duct system

The duct system provides adequate airflow to the air blower. Having inadequate ductwork or a leaky duct limits airflow and raises air pressure in your AC unit. A leaking duct also causes energy loss, which might raise your utility bills. Contact an HVAC specialist to repair and seal the ducting to resolve this issue properly.

Undersized Return Grill

Your AC unit can have a restricted airflow if the return grill in the ductwork is too tiny. A lot of air tries to squeeze through a small space, resulting in your air conditioning system making a whistling noise. Get in touch with your HVAC technician to install the proper-sized grill.

A Malfunctioning Blower

A broken blower could cause your air conditioner’s whistling noise. Contact a professional to repair or replace the blower motor.

High Air Pressure in the Compressor

Is your compressor making a whistling noise? This could be due to the pressure within your air compressor. If the pressure in your compressor is too high, it may cause more harm to your air conditioner.

So, if you hear a whistling noise coming from your compressor, turn off your cooling system and contact an HVAC specialist to resolve the problem.

An Oversized System

Your home’s air conditioning system is designed to move a specific amount of air. If the system is too large, it will carry more air than your ducting can manage, causing the whistling noise that you hear. Contact a professional to fix extra ducting or replace the air conditioner unit.


If you hear a constant whistling when you switch on your air conditioner in Spokane WA or surrounding areas, you should check your AC unit to look for debris, leaks, and poor installation in your cooling system. However, Hurliman HVAC professionals can determine the cause of the problem, and we will be able to provide you with an efficient solution to stop your air conditioning whistling noise.

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