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Portable Air Conditioner Making A Loud Noise? 7 Common Causes

Is the noise from your portable air conditioner irritating you or causing you to worry? Well, a bit of noise from a portable AC is expected during normal operation, but loud noises need to be assessed and resolved ASAP.

If your portable AC is making a loud noise, it could be caused by serious issues like loose parts, a bad compressor, or a refrigerant leak. Alternatively, the loud noise can also be from the AC standing on a hard surface, a high dB rating, bad installation, or a HIGH fan setting.

In this article, you’ll read about the 7 reasons causing your portable air conditioner to make a loud noise. We’ll also tell you how to silence your cooling unit, or at least reduce the noise.

7 Reasons Why Portable Air Conditioner Making A Loud Noise

1. AC Fan is Set on HIGH

Portable air conditioners have a fan as one of their many features. The fan’s primary function is to blow the air that has been cooled in the compressor throughout the room.

How fast a portable air conditioner’s fan circulates the cold air to the room is determined by the fan speed, which can be set at HIGH, MEDIUM, or LOW. 

Reverse cycle portable ACs also have an AUTO fan mode. When using this mode, the fan speed is determined by the room’s temperature.

Fixing a Noisy Portable AC with the Fan Set on HIGH

If your portable AC is noisy due to a HIGH fan setting, you may have to choose between faster cool air distribution with a bit more noise and a slower air distribution with less noise. 

You can also opt to set the fan on HIGH when you are out of the room and set it at LOW when you are in the room.

2. High Decibel Rating

According to the US Department of Energy, room ACs should not exceed an indoor sound power level of 60 decibels (dB(A).

That equates to the level of noise from normal conversations and is safe for your hearing health. Until 80dB, the noise level is still safe even though it can get annoying. But noise levels above 80dB begin to be dangerous for your hearing with hours of exposure.

What this means is that a you shouldn’t just be worried about your AC functioning properly, but also need to be concerned about preventing hearing damage.

Luckily, most portable ACs have a normal noise level range between 40dB and 60dB. Any noise range beyond that will make your portable AC sound like it’s being too noisy.

Irrespective of the dB rating, if your portable air conditioner seems to make a louder noise than it did in the beginning, you should check for causes and do something about the noise.

Fixing a Noisy High-Decibel Portable AC

As much as we hate putting it this way, “choices have consequences”. So, if you purchased a portable AC with a noise range beyond 60dBA, it might be too late to make a difference.

Opting for a low-decibel portable AC right from the beginning is the best solution in this case. That could mean seeking the advice of an expert on the best low-decibel ACs before making a purchase.

You can, however, opt to reduce the noise by using a carpet or some soft material under the portable AC to cushion the noise. 

Make sure you don’t insulate your AC by covering it with blankets, as accidentally blocking the AC’s airways can cause the unit to overheat and become damaged.

A loose part is one of the most common reasons your portable AC might be making a loud noise, especially if you have an older unit.

3. Loose Parts Inside AC

Portable air conditioners have moving parts. With time, these parts wear out or get loose, broken, or can even detach entirely.  

This is especially true of the caster wheels, but the fan blower and the outer casing of your portable AC can also be affected. 

Loose, broken, or missing parts can cause the portable air conditioner to vibrate more, and this vibration will produce loud noises.

Fixing Loose Parts on a Portable AC

If you have loose or broken parts on your portable AC, you’ll need to have them replaced or repaired to reduce the noise they make when your cooling unit is on.

For example, the caster wheels on your portable AC work on the pivot principle and once the center of the wheel is offset from the pivot point, it can easily become noisy.

We advise you to call an HVAC expert to assess and repair any broken or loose parts in your portable AC. Doing it yourself will often lead to additional damage to the unit.

4. Bad Compressor

A portable AC will make a faint intermittent vibration during normal operation. But, if your portable air conditioner is making a loud rattling noise, that could mean a bad compressor. 

One of the issues that could make your compressor rattle is worn-out isolation feet. These rubber feet support the compressor at the base. 

If the isolation feet crack or disintegrate, the compressor loses balance and begins to make noises when your portable AC is running. 

Alternatively, a noisy compressor could also indicate that the cooling process in the compressor isn’t going right, that the electrical voltage is not at the required level, or that the electrical connections are faulty.

Fixing a Bad Portable AC Compressor

The compressor is the heart of your portable air conditioner. If it’s malfunctioning, you won’t be getting any cold air blowing from the unit.

Compressors are a delicate part of your cooling unit and you should not risk causing further damage. As such, we recommend that you fill the form at the bottom of this article and get connected with a reliable AC technician. 

5. AC is Standing on Hard or Unleveled Surface

A vibrating portable AC that is standing on a hard or unleveled surface will not just move slowly from its position, but it will also produce more noise.

Hard floors like tiles and hardwood do not cushion sound but tend to amplify it. Softer surfaces are therefore more suitable for keeping a portable AC quiet.

Fixing a Portable AC that’s Noisy due to Hard or Unleveled Surface

First off, ensure your portable AC is sitting on level ground to avoid any noises from the imbalance and prevent your cooling unit from tipping over from the slow movement caused by the vibrations.

In place of a hard surface, place your portable AC on a carpet or improvise a soft surface with rags, a blanket, or towels.

You can also opt to buy sound-absorbing floor mats to soundproof your portable AC and protect your floor at the same time.

Balance From Puzzle Exercise Mat with EVA Foam Interlocking Tiles, Black, 1/2″ Thick, 24 Square Feet

6. AC is Not Installed Properly

If your air conditioner is making a loud buzzing noise, it could be that the window installation was done improperly. 

Improper installation could mean that the duct and window panels are not held securely in place and are, therefore, making a rattling sound when the AC is in operation (or even when the wind blows or it rains).

Fixing a Portable AC that’s Not Installed Properly

You should first ensure that the foam seals are properly positioned. You’ll want to check that the window panel assembly fits properly in the window opening and that the window is closed properly.

If you want a tighter seal, you can use duct tape to seal the joints or any presenting gaps. Be sure to use the no-residue duct tape to avoid leaving stains on your window.

3M 2425 P2425 Residue Duct Tape, 2425-HD, 1.88 Inches by 25 Yards

See this LG video for an idea on how to secure your portable AC window installation.

7. AC is Frozen (Refrigerant Leak)

Believe it or not, your portable air conditioner can freeze up with consistent use. 

This happens when the refrigerant leaks and can cause your portable AC to produce a buzzing noise.

Fixing a Frozen Portable AC

There is no shortcut around this one. You’ll need to call an expert HVAC technician to assess and repair your cooling unit. 

You can hasten the repair process by filling the form at the bottom of the article and letting us connect you with a professional HVAC repair service near you.


  • Jake Alexander

    Jake is a freelance writer from Pennsylvania who enjoys writing about science and sports. When he's not writing for Temperature Master, he can be found watching the NFL or playing basketball with his friends.

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