window ac making noise

Tired of having your sleep, favorite show, or a conversation disrupted by a noisy air conditioner? Trying to figure out how to quiet a noisy window air conditioner? Whether your cooling unit is new or old, a whistle, rattle, or thunk in the night is disruptive and irritating.

How to reduce air conditioner noise depends partially on the model and how it is mounted in the window. However, it mostly depends on the type of noise the unit is making. The best way to quiet a noisy window air conditioner is through regular maintenance, ensuring the unit is properly secured, and any loose parts are tightened.

Window air conditioners make a variety of sounds that may indicate potential problems or issues that need to be addressed. In this article, I’ll discuss the different sounds you may hear from your cooling unit, what the noise may indicate, and how to quiet or mute noises.

Note: For information on quieting other HVAC units or appliances, please see our articles: How to Quiet a Noisy Furnace Blower, and, How to Quiet a Noisy Air Return, and How to Soundproof a Dishwasher.




15 Types of Window Air Conditioner Noises

Window air conditioners are usually seasonal appliances mounted in a window opening to provide cool relief to a small area. Unlike central air units that mount outside the building, the small window conditioner is inside or partially inside the space it is cooling. The location means it is closer and more directly part of the living area, so any noises it produces will be more disruptive.

All A/C units make noise. It is the frequency of loudness of the sound that makes it disruptive and annoying. If the cooling unit begins to make a new sound, then check it out. The following is a list of noises a window air conditioner may make and what it could mean:

1. Whistling

A leaf or other debris could be caught in the blower, and the air movement is causing a whistle. A loose part or belt can also cause a whistling sound.

2. Squealing Noise

Some units start up with a squeal, but a persistent sound usually means a fan or blower motor, or the blower wheel and housing are failing. It can also indicate that a bearing is wearing out.

3. Screeching

A compressor will screech if it builds up too much pressure. If it is a pressure issue, the machine should shut off automatically. A leaf in the fan blades can also make a screeching sound, as can a bearing.

4. Crackling Noise

This noise can indicate dirt or debris is caught in the unit. Ice build-up due to a faulty condenser will also make a crackling or popping noise.

5. Clicking Noise

Many units normally click when they start or shut down. However, if it is frequently clicking on or off, there may be a problem with the unit’s thermostat, an electronic component, or relay switch.

6. Pulsating Noise

A pulsing sound can indicate that the compressor is loose. The bolts that hold it down may have vibrated loose, or the rubber pads that it sits on have deteriorated and need to be replaced.

7. Rattling Noise

Window ac rattling noise could indicate a leaf or twig is inside the unit. It could also mean the window mounting is loose. If the sound is coming from within the product, it could mean a part like the fan has come loose. If it is none of these, then it could be an electrical conductor or component that is chattering, which can cause damage to the compressor and other parts.

8. Clanking

Indicates that something may be loose in the A/C or there is a broken component in the compressor. A clanking noise can also mean that the blades of the outdoor blower fan or indoor blower may be hitting something, or are wobbling out of balance.

9. Grinding

A grinding noise may prove to be a failing condenser motor.  Grinding can also be attributed to a fan blade rubbing on something, or that it a blade is broken.

10. Window Air Conditioner Sounds Like Popcorn

A popping or crackling sound may be caused by humidity condensing, or icing up on the coils. The thermostat may be set too low, or the drain may be clogged. Another possibility is there may be a leak in the housing, and rainwater is seeping in and causing problems.

11. Beeping Sounds

Many cooling window appliances beep when they are first powered up or are being programmed. However, a unit that beeps more frequently may mean that a power supply is failing or an internal relay is faulty.

12. Thunking Sound

The compressor may make a normal thunking noise when it starts up. If it isn’t a “normal” sound for your machine, check that the rubber feet the compressor sits on to absorb vibration; they may have vibrated loose or dried out and cracked or split, which can lead the compressor to make a buzzing or thunking sound.

13. Banging Noise

Often indicates that something may be broken or loose within the compressor. The banging could be caused by the air filter hitting the grill when it starts a cooling cycle, or be due to a loose or broken part.

14. Buzzing Noise

This is a sound that could indicate several different concerns. There could be a stick or leaf stuck rubbing against something. It could reveal that a part has come loose and needs to be tightened. A buzzing or burring may prove to be an unbalanced or loose fan, or that the fan motor may be loose or failing.

It may indicate that something is rubbing against the copper lines too. An investigation may show that there is a coolant leak, or possibly the filter or condenser coils need to be cleaned.

15. Humming

Humming is a normal electric sound but may indicate vibrating of the refrigerant coils that can lead to bigger issues. It may mean there is dust or dirt within the A/C housing, so the unit needs cleaning. A hum or buzz could also be an electrical problem, especially if the compressor doesn’t start, which could be a loose wire or a motor failing.

Other noises may indicate either normal sounds or that there is a problem. Additionally, noise from outside can penetrate through the openings and cracks around the air conditioner so that the disruptive sounds could be coming from elsewhere.

How to Quiet a Noisy Window Air Conditioner

There are several steps to check if your window air conditioner is making too much noise, or has begun making a new sound. Attempt to identify where the sound is coming from, and then work to eliminate the noise or narrow down what it could mean.

Step 1: Make sure the A/C is properly installed in a window in a solid wall.

It should be level from side to side and have a slight tilt toward the back to prevent moisture pooling. Check that the unit is receiving adequate voltage too.

Reinforce the brackets and supports if the wall isn’t solid. Ensure the unit has been installed and secured according to the manufacturer’s installation instructions. Tighten any loose parts or fasteners which may rattle or vibrated.

Make sure gaskets, seals, and weather-stripping are where they should be. Also, check that the side or top closure panels are in place and fastened tightly. Use spray foam or caulking to fill small cracks or openings. If adjacent windows rattle, tighten, and, if necessary, apply new putty or caulking to cancel vibrational noise.

Step 2: If the noise is coming from inside the window unit, check for twigs, leaves, or other debris. Wipe clean or vacuum the unit to remove dirt and debris. Remove any insect nests, and check that the air filter and screens are clean. Also, clean the fan blades and condenser coils.

Check for any loose screws, bolts, nuts, spring clamps, belts, or parts and tighten or replace as required. Make sure everything is secured as it should be. Remember to check the unit housing pieces, including the front cover plate.

Step 3: Check that the fan blades are aligned and rotate freely. Straighten or tighten if necessary. Do the same with the cooling fins if required. Damaged fan blades can create many noises and also cause damage to the motor too.

Observe that the rubber vibration pads on the compressor’s feet are still supple. Replace the pads if the rubber is split, cracked, or dried out. Check the other noise-cancelling gaskets, washers, and grommets and replace them if necessary.

Tighten nuts and bolts if they are loose. If belts are worn or damaged, install new belts. If parts are broken and can be replaced, exchange them using proper parts. Call for service if the fix is outside your comfort zone.

Step 4: Some squeaks and squeals may be the result of insufficient lubricant. Use white grease or light machine oil to lube moving parts. The fan motor, fan, blower wheel, and bearings could be lubed at the start or end of each season.

If a bracket or joint is making sound, apply some grease there as well. Alternatively, insert rubber or silicone strips to absorb vibration between parts that rub and tighten. Don’t lube or oil electronics or rubber/plastic parts.

If all else fails, you may want to get a new quiet window air conditioner. All air conditioners will make noise, and while a well-built A/C unit may be more expensive, it should be quieter and last longer.

How to Properly Install a Window Air Conditioner

Installing a window A/C unit is a quick solution to a hot problem. The unit is designed to fit inside a window opening and blow cool air into a room.

Ensure the unit will fit the window, and is large enough to cool the space. Read the manufacturer’s installation instructions before beginning, and follow their directions. 

Mark the center of the window opening you’re going to use, making sure it is close to an electrical outlet. The unit may have sharp edges or corners, so be careful removing it from the box.

Open and prepare the window and opening as per instructions. Fasten the side or top panels, and then insert the unit into the window opening – a second pair of hands is advisable for this step.

Close the window onto the A/C to secure it in place, most of the weight is outside the building. Fasten all brackets and extend the side or top panels to keep the weather, birds, and insects out. Install foam or insulation pads if supplied, and plug in the unit. Program using the remote or touchpad, and enjoy the cool air.


Window air conditioners all make some noise. The type of sound and how frequently it occurs may indicate that the unit requires cleaning or maintenance, or that it wasn’t installed correctly. I’ve tried to address a variety of noises or pitches a window A/C can emit. However, a whistle to one person could be a squeal to another. 

If your cooling appliance is making unusual sounds, make sure it is installed and leveled, clean it, check for loose or worn parts, and lubricate moving parts. Hopefully, you found this article useful.  Pass it on to someone who may find it helpful. If you have any tips or suggestions to add, your feedback is appreciated

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Author S Krone

A lawyer never retires. So I would just say that I am not as active as I used to be. Now I simply dedicate myself to fishing, my hobby, and my grandchildren. For Business Finance News I write about legal aspects of mortgage policies, mostly regarding the rights of policyholders. I also have articles about personal injuries.

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