Is Low Airflow Causing a Whistling Noise in Your AC?

How low airflow can result in a whistling noise in your HVAC air conditioning system? Explore solutions for air conditioner air filter and air conditioner AC issues!

Updated on Oct 22, 2023
5 min read
Is Low Airflow Causing a Whistling Noise in Your AC?

The high-pitched, grating, whistling sound coming from your vents can be annoying. But, it indicates a larger problem – that your Northern California system is experiencing low airflow. This basically means the system is not getting enough air through the return vents.

This guide will talk about four common problems that can make an air conditioner whistle.

What Does Low Airflow Mean?

The blower in an air conditioner is responsible for circulating air throughout the home. However, in case the blower is not receiving adequate supply of air, it can essentially become starved for air. This can be because of something restricting or blocking the airflow. There is increased pressure and velocity within the system when it is starved for air. This means that you will begin hearing a loud and high sound.

This whistling is similar to wheezing. When you can’t get air in through a blocked nose, your nostrils produce a similar high-pitched sound. However, when you are breathing normally, there is no sound. Whistling sound from an air conditioner may sound annoying. However, it does alert you of a problem within the system.

There are several reasons for an air conditioner to be making a whistling sound because of low airflow. It is important that you get the problem fixed right away since it can cause severe damage to the system. It can also increase your energy bills dramatically.

Causes of Low Airflow

1. Dirty Air Filters

Filters need to be changed or cleaned frequently or else they clog up the system. The air filter is vital to the indoor air quality as well, which is why you should not neglect maintaining it. The air filter works similarly to a strainer used during cooking. It picks out unwanted dirt, debris, and other contaminants from your space. However, a filter that gets too dirty is not able to allow for airflow.

This restricts movement, which can also result in overheating problems. It is important that you change the air filters once every 3 months or as per manufacturer recommendations.

2. Blocked Supply or Return Vents

Return vents are the large vents that are generally located in a staircase, hallway or some other open area. Your system will not get enough air if there is something bulky, large or heavy, like furniture blocking them. Vents can get clogged the same way as air filters. Hence, you need to make sure there is no dust or debris the clogging the vents and suffocating them.

Supply vents are responsible for providing air to the air conditioner. Your system won’t have enough air flow if these are blocked by furniture. You should remove all furniture in front of the vents and clean the return vent grill. Make sure you open the vents, even the ones located in unused rooms.

3. Closed Dampers

Dampers can be shut for preventing air from being delivered to certain parts of the home. You should locate the damper lever and make sure they are opened for allowing airflow.

4. Closed Doors

Supply air will need to sneak through small gaps to return vents if there are too many closed doors in the house. This will cause the blower to work harder for pulling in air, which can result in a whistling noise. Opening doors in the house should help with this problem.

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