9 Different Noises Your AC Is Making [Quickly FIX Them]5 min read

by Ben | Last Updated: October 2, 2021


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Just like noise that your car can make for some certain reason, it’s the same with your air conditioner.

Different noises are caused by different reasons, that’s why it’s important to know what causes the noise your air conditioner is currently producing.

I prepared a list of 9 different sounds your air conditioner is probably making to help you recognize what you need to do.

9 Most Common AC Noises (What Causes Them & How To Fix Them)

1. Buzzing

Buzzing sound can be heard inside of your home just near the air handler and outside of your home.

This is usually a sign of an electrical problem.

When it comes to electrical problems, there could be several reasons:

  • Loose parts
  • Failing Motor
  • Dirty Air Filter
  • Loose Fan Blades & Outdoor Fan Motor
  • Refrigerant Leaks

📍 Note: If your air conditioner doesn’t produce any strange noise, but it isn’t cooling on the inside of your home – it’s most likely a refrigerant leak.

2. Banging

If you hear a loud “banging against the wall” noise from your outdoor unit, it’s probably a compressor.

Parts inside the compressor became loose and because of that – they are creating that banging sound.

This is a serious problem as it’s hard and expensive to repair compressors. Most professionals don’t know how to fix it as it’s a complicated process, so you might be better off buying a new compressor.

3. Hissing

The hissing starts when there’s a duck leak, misfit air filter, or most likely a refrigerant leak.

This sound might remind you of air going out of the balloon as it’s similar because the refrigerant is escaping the copper tubing due to high pressure.

Also, it could even be because your air conditioner got frozen. Check out our article on how to unfreeze your AC in 4 easy steps.

4. Clicking

A boring clicking sound is usually caused in two different situations:

When the AC is running, it might be that some small object got inside of your blower fan and it’s creating clicking noise because this object hits the fan every time it spins.

If you hear the same noise when you’re trying to turn on your air conditioner and it’s not working – it’s usually an electrical-related problem with the thermostat or compressor.

5. Squealing

Squealing noise is usually caused by a blower fan or bad compressor.

If you hear the squealing from the outside unit, then it’s probably a bad compressor or damaged fan motor.

If you hear it inside of your home, then it’s definitely a blower fan. Blower fan pushes the warm air out of your home and when the bearings in the fan stop working efficiently – it starts creating that boring squealing sound.

6. Humming

You should treat humming sounds like a warning issue because it’s not that serious, but it tells you that something is wrong inside of your air conditioner.

It’s usually refrigerant or loose parts that cause this problem.

It’s a warning sound because it can lead to bigger problems if you don’t inspect it further or maintain your AC.

The only time humming sound is more dangerous is when your air conditioner can’t be turned on. Then it’s usually a problem with the motor.

7. Rattling

Rattling sound is usually a sign of loose parts or twigs that clogged the whole unit.

I notice that most of the time the fan starts making rattling noise because it got loose.

On the other side, the problem could be with an electrical contractor which could possibly damage other components.

📍 Tip: First things first – inspect carefully for loose screws.

8. Pulsating

If your air conditioner is making pulsating noise – it’s all good.

However, if your outdoor unit is producing this kind of nose then some parts need to be replaced as soon as possible.

9. “Helicopter”

If your air conditioner is sounding like a helicopter, you most likely have problems with outdoor units or even with indoor blowers.

It’s usually a broken belt that’s causing this type of sound.

The problem could sometimes be simply because a piece of paper can get into your blower fan and cause this helicopter sound.

How Can I Make My Air Conditioner Quieter?

If you inspected the air conditioner carefully and there’s nothing wrong with it – it might be that AC is old and is producing weird noises by itself.

You can check out the list of most quietest air conditioners on the market. Maybe it’s time to upgrade?

But if you want to keep your AC, here’s a couple of ways you can make your air conditioner quieter:

1. Sound blanket

From my experience, the compressor is usually the reason why AC is making noise.

Go ahead and remove the top of your outdoor unit and put a sound blanket just above the compressor. 

This won’t get rid of noise totally, but it will at least decrease the noise.

2. Noise barriers/fencing

Same as people are building those noise barriers to block the noise coming out of the street, you can do something similar with noise fencing.

You should build noise fencing about four feet away from your unit, so it doesn’t block any airflow coming in.

I personally haven’t tried this by myself, but I’ve seen companies and offices doing it.

3. Noise-blocking curtains

You might have heard about it and they work perfectly.

It will reduce the noise and if you put some big houseplants around the windows facing the air conditioner – you’ll see drastic change.

Sometimes you might hear two different sounds (e.g. clicking and banging), so just implement the solution for both of them.

If you found this article helpful, go ahead and read our article on air conditioner money-saving tips and tricks.

Benas Leonavicius
Hey there! I am Benas, the founder of Home Caprice. Thanks for reading the article, I hope you were able to find what you were looking for. Me together with my team, are here to simplify heating and cooling for everyone. If you want more details about the website and our team, please check the about page.