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Loud Window Air Conditioner in a Brick Building

How to Quiet a Noisy Window Air Conditioner (10 Fixes)

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Air conditioners are a lifesaver during the hotter months of the year. Many households rely on window-mounted units rather than the typical central AC system found in most homes.

Unfortunately, that relief can be short-lived when noise comes into the picture. A noisy window AC system can get in the way of everyday activities and even make quiet conversation impossible.

We’ve put together a thorough guide on tackling window air conditioner noise. Below, you’ll find the most common causes of a noisy window air conditioner, along with some troubleshooting and repair tips. With these pointers, you can rest easier and enjoy cooling comfort with significantly less noise.

Quieting a Noisy Window AC

Window air conditioning systems work hard to cool small-to-medium-sized rooms. As a result, they’re bound to be noisier than a central AC unit or a ductless mini-split AC system. And since these units are mechanical systems, there are many parts that need maintenance or that can fail outright. These failures can contribute to any excess noise issue you’re dealing with.

Most common window AC noise complaints can be solved with regular maintenance and good installation. If any of the following noises are coming from your window unit, here is how you can fix and reduce air conditioner noise.

1. Pulsating Noise

During normal operation, you may hear a surging or pulsating noise that alternates between soft and loud. That rhythmic pulsating comes from the sound waves generated by the AC compressor’s movement. If the window AC system isn’t insulated well enough, then you may hear these sound waves transmitted through the unit.

To troubleshoot, remove the window AC unit’s back panel and look for the compressor. Check the rubber isolation feet and make sure they’re not damaged or missing. If so, replace them.

Refrigerant lines can also transmit these noises, especially if they’re contacting the wall in some way. Check the lines inside the unit and, if possible, gently nudge them away from the walls of the unit or any other hard surface.

2. Loud Noise When Starting

It’s normal for your window AC system to make a little noise when starting up. What’s not normal is a loud bang or hum on startup. Either issue is usually a sign of capacitor or compressor failure.

Compressors need plenty of voltage to start up. Think of capacitors as small batteries designed to provide a short, but strong burst of voltage to the compressor. A failing capacitor won’t give your window AC the juice needed to start up normally.

The end result is a compressor that starts up with a loud bang or hums loudly on startup. Replacing the capacitor may help alleviate these issues.

3. Sounds Like a Jet Engine

Perhaps your window AC unit sounds like it’s ready for takeoff. A bad blower fan bearing or a damaged blower fan can cause roaring sounds that mimic a jet engine.

A lack of lubrication can also lead to jet engine-like noises. The fix usually involves adding the right lubricant to the window AC unit’s moving parts, including the blower fan.

Meet “Mitch”, the poorly maintained window AC unit.

4. Loud Buzzing

Some window air conditioners occasionally make loud buzzing noises. It’s when that buzzing noise becomes constant that you should worry.

In most cases, loud buzzing can be pinpointed to a malfunctioning AC compressor or compressor. Both can make buzzing noises as they fail due to power delivery issues. Vibrations from loose components can also cause buzzing within the unit.

The window AC unit may also buzz if the fan blades are out of balance. You should have your AC technician replace the fan.

5. Makes Noise After Shutting Off

A broken support spring can cause the compressor to slam against the case of the window AC unit as it shuts down. Unfortunately, you’ll need to replace the entire compressor to solve this problem. That’s because the affected spring is actually within the compressor, which itself is sealed.

If you hear a crinkling or tinkling noise after shutoff, on the other hand, there’s nothing to worry about. Those sounds are usually metal components that are expanding and contracting as surface temperatures inside the unit change.

Your window AC system may also be equipped with a damper. If the damper works automatically, then you may hear it close when you shut off the unit.

6. Clicking Noises

You’ll hear a soft clicking noise when you turn on your window AC system. That’s normal and it’s due to various relays and other components activating inside the unit. If you hear clicking noises but can’t get the unit to start up, then you may have a faulty capacitor on your hands.

If you hear a constant clicking sound while the window AC unit runs, then it may be due to a damaged blower fan. Carefully check the fan blades for any signs of damage. Also, make sure the blades aren’t in contact with any nearby surfaces.

7. Loud Humming Noises

A loud humming noise during operation usually points to an electrical issue. For instance, a burned-out fan motor will hum loudly when the unit is turned on. A failing capacitor and/or compressor will also hum.

8. Water Dripping Sounds

Your window air conditioner does more than just cool the air in your room. It also removes excess moisture from the air. This excess moisture ends up inside the unit as condensate.

There’s a drain pan inside the window AC unit where condensate collects. Some of this condensate is collected and thrown back onto the coils to better enhance the unit’s cooling performance. The rest is pushed around and eventually out of the unit via a drain hole or drain line. Either way, this is perfectly normal and nothing to worry about.

If you see excess condensation dripping out of the unit and into the room, however, then you may want to check the unit. Make sure it’s tilted properly so that the condensate drains outdoors rather than indoors. Also, make sure the drain hole or drain line isn’t clogged with debris or mold growth.

Some units may have a rubber plug on one of the back corners of the unit. Remove this plug to release excess condensate and replace the plug afterward.

9. Annoying Whistling Sounds

A high-pitched whistle is usually the calling card of a partially-blocked air vent. Pinpointing the cause of the obstruction, whether it’s debris buildup on the vent, an accidentally closed vent, or a dirty air filter, will help reduce the unwanted noise.

10. Popping & Clicking Noises

If your window air conditioner sounds like a popcorn maker, don’t be alarmed. In most cases, it’s just condensate freezing or thawing on the coils. A simple fix involves raising the thermostat by a few degrees to avoid freezing the condensate.

Low refrigerant levels can also trigger popping and clicking noises due to ice buildup on the coils. Have your AC technician check refrigerant levels within the unit and make repairs if necessary.

Reasons For a Loud Window Air Conditioner

Now that you know what to look for when it comes to window air conditioner noises, it’s time to find out why these noises happen in the first place. The causes vary widely, but most of the underlying issues can be fixed with a bit of patience, time, and a few basic tools:

  • AC is Overworked! – An overworked air conditioner is going to struggle to cool your space. The stress on the unit can lead to early wear and tear on the mechanical parts of the unit. Give the unit some help by using some efficient tower or floor fans to circulate the cooler air.
  • Dirty Air Filter – A dirty air filter can severely restrict or even block airflow to the window AC unit. This also adds stress on the unit and eventually leads to the compressor and other components failing. Changing the air filter on a regular basis helps prevent these issues.
  • Filthy Compressor Coil – Debris can build up on the coils over time. Too much debris can block air from passing through, making it harder for your window AC unit to cool your home. Cleaning the coil not only restores performance but also reduces noise and increases the unit’s longevity.
  • Unstable Mounting – The window AC unit can make noise if it isn’t mounted properly. Adding additional support can help quell vibrations and other unwanted noises.
  • Bad Fan Bearing – A failed bearing within the window AC system fan can cause grinding and howling noises. Have your AC technician check and, if necessary, replace the fan bearing or the blower fan itself.
  • Low Refrigerant Levels – Low refrigerant levels do more than just rob your home of cool air. They also place stress on internal components, making them wear out faster than expected. This wear and tear are also accompanied by a variety of noises. Checking refrigerant levels regularly can help prevent these issues from happening.


Just because your window air conditioner makes noise doesn’t mean you have to live with it. Most noises can be vanquished with a little troubleshooting and some elbow grease. With the above guide, you’ll be able to enjoy some peace and quiet for once.

Keep in mind that most window AC units have a lifespan of roughly 8 to 10 years. If yours is that old and suffers from noise issues, then consider replacing it entirely with a brand-new unit. Not only is a complete replacement more cost-effective than constant repairs, but the newer units are also more efficient and eco-friendlier.

Tom Davidson

I'm a Design Engineer, husband, and Dad to two. I have a taste for building, playing bad golf, and tackling all kinds of home improvement projects. Read more about the SPT Team.

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