How To Soundproof An Air Conditioner: The Ultimate Guide

How to soundproof an AC

This AC is almost 15 years old and sounds exactly like it!

Soundproofing the air conditioner has been on my mind for a LONG time. We have 2 window AC units at our home and both of them raise a racket every time they’re turned on.

When I started working from home, I became desperate. I finally did a little research and found two concrete solutions that seem to have really worked for a lot of people.

So, here’s how to soundproof an air conditioner:

    1. Buy a soundproof blanket: for a noisy compressor
    2. Put an acoustic sound barrier behind your AC

Let’s dive right into these, shall we?

Air Conditioner Soundproofing Method #1: AC Compressor Blanket

If you know for sure that it’s your AC compressor that’s giving you noise issues- this is probably the best thing you could get.

Note: In case you’re not sure what’s causing the noise- feel free to skip ahead to the part where I describe the various sounds an AC makes and what their most likely causes are.

As for the soundproof compressor blanket, it’s made up of a rubberized material that’s generally used for blocking sound inside car interiors.

These can be easily installed by anyone onto any compressor, regardless of type or make of your AC- soundproof compressor blankets are pretty much universal.

You might be thinking- hang on, won’t the compressor overheat if we cover it with an insulating blanket?

Good question- but don’t worry, it won’t.

That’s because the compressor is internally cooled and it’s performance doesn’t really get affected by the soundproof blanket around it.

They’re mostly priced under $80, and I would recommend you check out the Brinmar soundproof blanket- it’s available on Amazon and is quite popular- with 74% positive reviews, as of the time of writing this post.

How to Install The Brinmar Soundproof Blanket For Your Compressor

Like I said, you can install the soundproof blanket in any type of AC- it’s a universal size and if you’re a split AC or window AC owner, you can go ahead and get the standard Brinmar soundproof blanket.

The product will also fit most central AC compressors, up till 60,000 BTU(British Thermal Unit). If you have a higher BTU compressor, they also have a model for that but only seem to sell it through their website

The Brinmar soundproof blanket manufacturers claim that it is designed to fit over 500 models of compressors, including brands such as:

    • Bristol
    • Copeland
    • Tecumseh
    • Hitachi
    • Carlyle
    • Toshiba

In order to install it, all you need is a screwdriver to open up your AC unit and access the compressor. If you’re not comfortable opening up the AC yourself, you may want to call a technician to install the blanket.

The blanket comes with hook and loop straps for easy fastening. It’s designed in a way to allow for varying girths and heights of different compressors as well as adjust around the inlet/outlet pipes connecting to the compressor

The ONLY thing you need to ensure is that you’ve covered the compressor up nicely and that there aren’t any gaps left.

This is why there is plenty of overlap in the material so that you can wrap it around the compressor completely- especially near the points where the inlet/outlet pipes are attached to the compressor.

That’s pretty much all you’ll need to do really. You should notice a minimum of 4 dB or ~40% noise reduction as compared to without the blanket.

Take a look at this before and after video of the Brinmar blanket, for a better idea:

Air Conditioner Soundproofing Method#2: Place An Acoustic Sound Barrier Behind The AC

Quiet Fence is one such product that I found on Amazon. It’s made from HDPE(High density polyethylene) and is manufactured in a patented design- which is what lends the product it’s sound dampening properties.

You can place it behind your window AC or outdoor compressor unit as a barrier that blocks sound and doesn’t disturb the neighbours too much.

Just be sure to NOT put the fence right against the AC unit as that’ll block air flow.

In one order, you’ll get a pack of 2 fences with the dimensions- 43”(h) x 48”(w) x 3”(d).

These should be good enough to surround a window AC from behind or a even medium sized outdoor compressor unit. In case you have a bigger unit, you might want to get another set.

You can leave the fence free-standing but it’s going to keep getting knocked down by wind and whatnot, so I’d recommend fixing it to the ground with some garden fence stakes.

According to user reviews, Quiet Fence comes with pre-drilled holes, so it’s easy for anyone to install the fence stakes.

These are quite expensive though, and honestly, I think that you should try the soundproof compressor blanket first and only use this as a secondary solution, if you can afford it, that is.

Alternatively:

If you’re good with DIY stuff, you could make your own sound blocking fence and reinforce it with fibreglass, which is a very good soundproofing material. Don’t forget to use green glue if you are going down this path!

How Noisy Are Window AC’s Usually?

From personal experience(I’ve owned multiple window ac’s for the last 15 years) and through reading about this topic online as well, one thing has become very clear:

9 times out of 10, a window air conditioner is going to be LOUDER than a central or split air conditioner.

The biggest reason for this is that no window is ever going to be the right size for the AC.

It’s always going to have a sliver of a gap between the frame and the AC from where sound can pass through.

Secondly, if a window AC is improperly mounted on the window frame, it’s going to make a lot of noise by vibrating the frame and walls surrounding it, especially if there isn’t any padding stuffed into the gap between the window frame and the AC.

Thirdly, since they are small in size, internal parts in window AC’s seem to wear out quicker than other AC types, which contributes to the noise

Just please don’t install a window AC on a concrete wall or brick wall, if you can avoid it, because these materials conduct sound really well.

If a window AC is installed near a wall corner, you’re going to have even more sound reflections. Best to plan the installation accordingly, if you can.

If you can’t, then of course, there are other things you can do- which I’ll talk about in a bit.

Lastly, the sort of obvious point- you should expect some sort of noise increase as your AC gets older and the parts start getting worn out.

If it is a premium model, then of course, it’s not going to give as many noise troubles.

How Noisy Are Central AC’s Usually?

Central AC’s don’t usually give a lot of noise issues indoors because the compressor unit is, in most cases located outside. One simply doesn’t get to hear much noise, unless the compressor is ACTUALLY really loud and you’re in a room right next to it.

Given the fact that these are bigger units than window or split AC’s, if a central AC compressor makes noise, it can raise HELL in your neighbourhood and sometimes, even inside your home.

The most common noise complaints with Central AC units are due to:

    • Compressor being too loud- mostly felt outdoors and quite likely to happen after 5-6 years of owning the product
    • HVAC vents causing noise- felt indoors but less likely to happen

How Much Noise Do Split AC’s Make?

Split AC’s seem to be the quietest of the lot. I’ve never owned one, but having seen them in other places, they have always been remarkably quiet.

To the extent that you wouldn’t even get to know when it’s on and when it gets turned off!

They perform better because, firstly, they are more premium than window AC’s. This means they are more sophisticated with how much noise they make.

Secondly, since they are wall mounted, there aren’t any of the structural noise issues of mounting an AC on a window.

Noise wise, these seem to be the perfect middle ground between a window and central air conditioner.

7 Common Noises Your AC Might Make And Their Likely Sources

Note: There can be many types of noises an air conditioner unit makes- such as rattling, squeaking, hissing, intermittent beeps, etc- and each of those can have multiple causes. The most COMMON source of these noises though, is the compressor.

#1 AC Makes A Popping Sound

There are a couple of reasons why this could be happening:

    1. The air conditioner compressor is sucking in the liquid refrigerant
    2. The motor fan blade is hitting something inside the AC
    3. Electrical problems- loose wires may cause popping sounds

If this happens, you definitely should shut down the AC right away and call a professional.

#2 AC Makes A Loud Rattling/ Vibrating Sound:

9 times out of 10, this happens because of the compressor.

I know because I’ve been dealing with this for a very, very long time.

The compressor is generally the noisiest part in any AC. This effect gets aggravated in a window AC because of the structural issues I talked about above.

Apart from the compressor, the second most common source of noise are the fan blades. They can be easily replaced, however.

Compressors though, aren’t so easy to replace.

What probably will be more cost effective is to get a soundproofing blanket for your compressor, the one I talked about in the section above.

And if you don’t want to invest one just yet, try ensuring that your window AC is mounted properly and that you’ve covered up the gaps in the window frame as much as possible.

#3 AC Makes A Loud Screeching Sound While Running

If you have a window AC, the first thing you should check is whether you’ve installed the front grille correctly.

Most owners are aware that the grille gets dirty very quickly and should be cleaned out under running water every couple of weeks, however, if, while putting it back, it isn’t installed properly, it can cause the screeching sound.

I know because… I’ve made this mistake before.

The other likely cause is worn out ball bearings inside the AC unit, which might not be rolling properly.

This is an easy fix, but you’ll have to call a professional for this.

#4 Air Conditioner Makes A Loud Screaming Noise

Some people also complain that their AC makes a loud noise, similar to screaming when starting up.

If this happens, you should turn the AC off right away and call a professional, as the probable cause for the screaming sound is a high pressure build-up inside the compressor, which can be very dangerous.

#5 AC Makes A Humming/Buzzing Noise When Turned On But Doesn’t Start

This usually happens because of the capacitor dying.

The capacitor stores electricity temporarily(think of it as a temporary battery) and is responsible for providing a kick start to the motor.

This kickstart is important because the motor needs more energy to start the first time than to continue running.

The other reason could be that your compressor’s fan motor has died out. If this is so, it will need to be replaced by a professional.

If you have a central AC unit- there’s an easy way you can check this. Take a wooden stick and rotate blades of the compressor unit with it.

This should provide the kickstart it needs to start working. If it still doesn’t turn on- you know that the motor isn’t working.

A note of caution:

Firstly, do take safety precautions when doing this- and if your AC is still unable to start and keeps buzzing, you should turn it off ASAP because it may burn the motor out.

#6 Air Conditioner Makes A Clicking Sound

This could either be an electrical problem or a small obstruction in the fan blades.

It’s probably an electrical issue if:

    • The clicking is very rapid and doesn’t have a pattern to it
    • It happens when you’ve switched the power point on but haven’t turned on the AC

This could be because of wiring issues, in which case you’ll need to call someone.

The second case is probably due to voltage fluctuations(quite uncommon, but might still happen), in which case you probably just need to wait it out or if it keeps happening frequently in your area- get a voltage stabilizer

If not these two reasons, the sound probably is just from a small obstruction in the fan blade that you need to remove.

If you have a window AC you might need to call someone, but if you have an outdoor AC, you could probably go take a look and remove the obstruction without having to open it up.

#7 Air Conditioner Makes A Gurgling Noise

This is something that can have many causes- however, the most likely one would be that there is a refrigerant leak.

Conclusion

In this article, I went through all the best ways I could find on how to soundproof an AC unit.

To recap, I believe the best two solutions in the market are:

    • Brinmar soundproof blanket for compressors- if you had to pick one solution for soundproofing your AC, pick this,
    • Sound blocking fence: Quiet Fence

Before ending this post, I’ll just say that the best cure is prevention. Consider buying a premium air conditioner next time you’re looking for one, and spare yourself the hassle of soundproofing a slightly cheaper one.

In my book, it’s worth paying a bit extra for the quiet and peace of mind you’ll get.

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