Excessive noise is an issue for so many people and an air conditioner with unknown issues can

send even the most patient person over the edge. From whistling noises to a full-on shake, rattle, and roll, the noises your air conditioner is making can mean any number of issues.

In this article, we’ll explain each noise your AC unit may make and what those noises might mean for your system. When you’re done with the article, you should be able to diagnose the most common air conditioner issues.

Whistling Noises

If you hear something that sounds like a whistle or a whine, you’re likely looking at a problem with the airflow through the unit. In this case, you’ll need to check the ventilation for the following issues:

  • Your ducts don’t match. It’s possible the ductwork you have connected to the air conditioner is too small and can’t accommodate the amount of airflow needed for your unit model.
  • The filter may be clogged. Filters are meant to catch dust particles and any other debris that can contaminate the air. However, once the filter is filled, it becomes increasingly difficult for air to find open spaces to flow through.
  • Part of the ductwork might have sustained damage. If your pipes and ducts are old, they may have kinks, dents, or cracks. When this happens, air can’t flow through easily.

A Loud and Inconsistent Unit

The noises coming from your unit may also be due to the size of the unit in proportion to the room it’s in, as well as the model or brand you’ve chosen to go with. Many modern window units are built to run for a specific amount of time and then shut off until temperatures get too high in the room.

If the AC unit isn’t the right size or strength for a room, you may find that it’s constantly turning on and off to try to compensate. It’s also important to note that cheaper AC models are made without noise dampeners. While buying cheaper may save you money upfront, it could cost you your sanity later.

It’s also extremely important to shut the unit off and address the issue right away if you notice the unit is constantly running and blowing out warm air. When this happens, it’s likely due to frozen coils. Coils will freeze most often when there’s a lack of airflow and the cold air condensates around the coils as a result.

Shaking and Rattling

If you notice your unit is shaking or rattling, it’s likely due to instability. If the unit isn’t placed on a flat surface or reinforced outside with added stability in the case of window units, it may struggle to stay still while running.

Typically, this issue can be resolved by adding more stability to the bottom. However, some instances may constitute calling in a professional:

  • Issues with the fan component. Part of the motor or internal fan may be damaged. If the fan or motor parts are hitting other internal components, it can make more noise and further damage the unit.
  • Projectiles in the ductwork. If the internal workings of the unit are fine, there may be freestanding debris in the ductwork.


Lastly, a common issue with AC unit noise is of squeaking or squealing noises. If you notice this ear-splitting problem, it likely means it needs maintenance. Here are some common things to check when this issue arises:

  • Bearings need oil. It’s possible the motor bearings are a little tight or may have some rust. If this is the case, you just need to give them a little bit of oil to lubricate the area again.
  • Broken blower belt. If the blower belt is broken, you can confirm by checking the belt near the blower fan. It’s possible the belt either broke or came loose from the fan.
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