Air Conditioner Making Noises? (How to Fix Common Sounds)

Air conditioners can become noisy, especially after years of use, creating distinct and separate sounds when running, turning off, and starting.

Though you can overlook the slight hissing sound, some are extremely loud and unexpected. And when you hear these loud noises, make sure you find the source as soon as possible!

By neglecting these mysterious sounds, you’re letting technical issues linger, letting them snowball into irreparable problems. The fix could be a mere DIY tune-up or even an expensive replacement job, and in the worst-case scenario, a complete replacement of your AC unit.

It’s better if you detect the issue sooner and resolve it immediately. If you want to know why your AC makes noise and how to fix it, read on:

10 Most Common Air Conditioner Sounds & Their Reasons

Pulsating Sound

Does your air conditioner make a bizarre pulsating noise? If it does, you may not have to worry because this sound doesn’t necessarily mean somethings wrong with your unit.

However, if the outside portion of your air conditioning system makes a pulsating sound, there may be a cause for alarm.

Moreover, if you can hear it within the house, it may denote something has broken inside the air conditioner and requires immediate replacement.

There is a high chance that the fault lies within the fan blades and motor. However, any loose part or panel can cause this pulsating noise.

Buzzing Sound

If the outer portion of your air conditioner constantly makes a buzzing sound, then it could mean:

  • Loose parts
  • The outer fan motor of the unit is about to break or is loose
  • There may be debris in your outdoor or indoor unit
  • The fan blades are out-of-balance or loose
  • Copper lines (which carry refrigerant from inside to outside and back may be rubbing against something)
  • Condenser coil requires cleaning
  • The air filter needs cleaning or replacement
  • The AC blower is out-of-balance or going bad
  • Frequent refrigerant leaks, which result in freezing up the air conditioner. If the AC unit doesn’t make enough cooling, it’s because of refrigerant leaks. It may create noise depending on the leakage and place

Related Article AC Making Water Sounds

Banging Sound

If the unit makes a loud knocking or banging noise, it’s a sure indication that there is a broken or loose part within the compressor; or maybe, your unit’s blower is imbalanced.

If there is a broken part, it could be of a:

  • Crankshaft
  • Connecting rod
  • Piston pin

In addition to that, a banging sound can also indicate that your air conditioner requires a compressor replacement.

Clanking Sound

Clanking noise is another indicator of an out-of-balance or a loose part. This noise usually originates from the outer unit, the condenser, which means something may have come loose and requires replacement.

It can also signify that the outdoor fan or indoor blower (including the blades) are loose, leading to the knocking of other parts within the unit. If ignored, these issues will get worse, causing more damage.

Squealing Sound

Fan and blower noises like squeals, rattles, and squeaks most likely stem from the duct system. If the outer motor or indoor blower emits a loud squeal, expect the unit to break down soon.

In addition to that, the blower housing and wheel also squeal if they malfunction. However, in most air conditioning units, this noise is normal during startup.

Ensure whether the squeal is normal for your air conditioner – or if it’s something new – before calling your HVAC technician.

Clicking Sound

If your AC unit clicks once during shutdown and startup, it’s considered normal. However, constant clicking isn’t.

This continuous clicking noise can be an indication of a failing thermostat or defective control.

Your air conditioner is a mixture of several electrical components; therefore, you must act as soon as you hear such sounds because it could turn into a much bigger problem if ignored.

Humming Sound

A humming noise usually isn’t a worrying one; however, it still signifies that something within your AC unit is not as it should be.

This sound comes from vibrations caused by the refrigerant piping or other loose parts, and if it’s left unchecked, it can cause serious maintenance problems.

Most of the time, buzzing or humming noises indicates electrical issues. If your AC unit’s compressor refuses to start – making a humming noise – chances are the problem lies with its fan motor.

Keep in mind that this noise can also be triggered by loose wiring.

Screaming Sound

If your AC unit makes a high-pitch scream or whistling noise, shut it off right away and call an HVAC professional.

The scream can be down to a refrigerant leak that can damage your unit and threaten the health of anyone inhabiting the house

Meanwhile, it can also signify a build-up of pressure within the unit’s compressor, which can be pretty dangerous.

And if your AC shuts off, as a result, don’t panic. In fact, this indicates that the sensor is functional, keeping you safe from a hazardous situation.

Chattering/ Rattling Sound

A rattling or chattering sound indicates that the AC unit is deteriorating, and most of its components are loosening.

It can also indicate the presence of debris such as leaves and twigs in the system causing this noise.

Also, an electrical contractor can cause this rattling/chattering sound, damaging your unit’s compressor if left unattended.

Additionally, your AC’s fan can make this noise when loosened. If this is the cause, check whether the unit’s casing has loose bolts or screws. After that, clean your air conditioner’s coils, and change the air filter.

Whirring Sound

If the air conditioner makes a whirring sound – like a chopper – the chances are it may have an issue with either the outer unit or the indoor fan (blower).

Usually, a whirring noise in the AC indicates that the blower motor has deteriorating bearings, a faulty outer unit blower, or a damaged indoor blower.

Furthermore, when the fan blades start to fall apart or come loose, a whirring sound occurs. And lastly, there could also be a broken or damaged belt somewhere inside the system.

But the issue isn’t always because of a faulty part; at times, a stray paper sheet or other debris can get stuck in the blower or the outer fan unit, creating a rapid whirring sound.

Ameristar Home Inset

How Do You Fix Your Loud Air Conditioner?

Fixing your loud air conditioner shouldn’t be a problem; there are several easy solutions to cut back any obnoxious sound.

But before you get going, make sure you have the necessary tools to fix the loud noise. These include a 4-in-1 screwdriver and adjustable wrench.

Without further ado, here are a few ways to fix loud sounds coming from your AC:

Straighten The Condenser Coil Fins

Maintaining the condenser fins can help increase the efficiency of your air conditioner. Make sure to straighten them using an AC fin comb. In addition to that, use a vacuum cleaner with suction and a blower to clean any leftover debris.

Tighten The Screws

Most AC units vibrate during operation, loosening the inside screws. This results in a rattling noise when operational.

Thus, if you hear a rattling sound, grab your screwdriver and tighten every loose screw you see. Even if there is no obnoxious noise, it’s better to ensure that all screws are in place and tight.

Removing Debris From AC Fan

Open your air conditioner’s cabinet and observe the blower for debris. If you find dirt or other types of junk in the blades, clean them.

This way, you’ll eliminate clanging and banging noises coming out from your air conditioner during startup. It will hardly take a few minutes to do this.

Straighten Your Bent AC Fan Blade

While checking for waste, make sure you check the fan blades too. If you find bent blades, put them back in their place, but do it gently to avoid any more damage.

Once you straighten your bent AC fan blades, look carefully at the screws meant to keep the blades in position. If you find any loose screws, tighten them up straightaway.

Over time, screws in the unit become loose because of frequent vibrations; this results in noise during startup.

Lubricate Fan Motor

A grinding and screeching noise while starting may denote a non-lubricated motor. Make sure to lubricate your AC fan motor with high-quality lubricant. Apply the oil gently to ports in the unit found near screws underneath the motor.

Related Article How To Oil AC Fan Motor

When To Call A Professional To Fix Your AC Noises?

HVAC Repair

Air conditioners make noises — some are normal, others are not.

Though most AC noises are easy to fix and don’t require professional help, some are tricky, and only an HVAC technician can fix them.

But how do you know when to call a professional?

Here are a few tips to help you out:

  • If the shutdown and startup sounds seem normal from cycle-to-cycle and not extremely loud, there’s no need to call in an expert
  • If there is a significant change in banging or pitching noises of the unit, chances are you may need a professional HVAC technician
  • Air moving within the AC should sound consistent and smooth during operation; if not, call a professional

Now that you know when you have to call an HVAC professional to fix your AC noise, it’s essential to contact the right HVAC professional to get the job done.

Here are a few things to look for:

  • Proper license and credentials
  • Applicable experience
  • Market reputation
  • Referrals
  • Cost
  • Emergency services
  • Home evaluation

Related Article More Information On AC Repair

Preventive Measures To Stop Future Problems

To prevent any future HVAC problems, it’s best to ensure timely maintenance and set up noise reduction systems. Nevertheless, here are three practical preventive measures to avoid future mishaps:

Schedule Regular Inspections

Make it a habit to inspect your air conditioner weekly or monthly. If you find it hard to do so, ask your HVAC technician to make bi-monthly visits to maintain your system.

They can pinpoint weaknesses in your unit and advice necessary repairs as well. In addition to that, to ensure your unit operates smoothly, it’s best to have it inspected every one or two years.

Install Noise-Reducing Barriers

Most air conditioners function under 55 dB; however, if your AC unit makes loud noises, you can install noise-reducing barriers. These include:

  • Quiet fence
  • Sound blanket
  • Noise-reducing barrier

There are other ways to minimize sound, but it’s better just to get your system checked and not pacify it with temporary fixes.

Call HVAC Professionals

If you notice any problem with your air conditioner, contact an HVAC expert. It’s the best option as they can foresee any significant technical issues with your AC before they may happen. This way, you’ll save money and time in the long run.

People Also Ask (FAQ)

How Does The Sound Blanket Reduce Air Conditioner Noise?

The sound blanket is specifically designed to absorb noise from an air conditioner and other electrical devices to minimize noise pollution. It’s made from sound-absorbent, impenetrable materials that can reduce noise up to 35 decibels.

For smaller spaces, consider a small portable AC.

Or small window AC

Why Does My AC Make A Loud Noise When Starting?

Loud banging coming from the unit during startup can be a sign of debris in your air conditioner. If there is no debris, chances are you have an unbalanced or loose fan, hitting against your HVAC cage.

Why Does My Air Conditioner Make A Loud Noise When Turning Off?

The compressor is a part of an outer unit that pumps refrigerant back and forth between the indoor unit. When the AC shuts off, the pump loses its momentum and hits against the compressor case. This creates a slamming or banging noise.

How Long Should An AC Fan Motor Last?

If the AC fan motor receives adequate cooling and is kept clean, it may last between 10 to 15 years. However, if the air conditioner doesn’t receive timely maintenance, it can fail within 2-3 years.

Is It Worth Replacing The Compressor On The AC Unit?

An AC’s compressor unit is pretty expensive to replace. Buy yourself a new air conditioner as it’s a better investment than fixing your old one. Feel free to contact NETWORX via the form below to get a quote.


Some AC sounds are normal during operation and occur in all the HVAC brands, so there’s nothing to worry about. However, some are unusually loud, indicating that something is wrong with the unit. Make sure to address all the unusual noises timely to avoid significant expenses.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.