Picture of a Typical Window Air Conditioner, Front View, Cool Side.

Fixing Noisy Window Air Conditioners

Anyone living in warmer climates and seeking to cool their bedrooms, living rooms, and other small to medium-sized living spaces, has probably grappled  with the problem of noisy window air conditioners. Indeed, we’ve installed units from five to twelve thousand BTUs in our windows at apartments, homes, trailers, and even basements, and have been frustrated by all the noises of the roaring fans, cycling compressors, snapping air cleaners within, and the window rattling as the installation loosens. Here, we give our how-to instructions and hints for fixing noisy window air conditioners.





Room units often thump, click, squeak, squeal, hum, whine, roar, and whir as their internal and external fans circulate the air around. These units can buzz and vibrate a lot as well. Then, when the thermostat turns them off, window air conditioners often make the similar noises, as their metal parts and the motors cool off.

Air conditioners, installed in a free window, work well for augmenting the primary cooling HVAC system in the home, if it has one. They’re cheap to buy (if not to operate).  Plus, you can move them from room to room as easily as people flit about. But fixing noisy window air conditioners you might need to do as they age.  Even the best AC units grower noisier over time.

Also, window AC units come in a big range of cooling sizes.  In fact, the larger units even accept 220 volt power for best performance.  But they have their drawbacks too; their loud operation being perhaps the most annoying one.

Fixing Noisy Window Air Conditioners: Warnings and Cautions

Turn Power Off

Before working inside a window air conditioner, be sure to disconnect it from mains power.  Otherwise, fatal electric shock can result, particularly in the 220-volt units.

Watch your Fingers  !

When you must work on the unit while it operates, avoid spinning fan blades.  These can pack enough force to seriously hurt a finger or hand that gets in their way.

Picture of the rear view of a typical window air conditioner, its hot side. Fixing Noisy Window Air Conditioners.
Typical Window Air Conditioner, Back View, Hot Side.

Fixing Noisy Window Air Conditioners: Tools & Supplies Needed

Screwdrivers and Nut Drivers

Have several sizes of each of the straight / blade, Philips, and star head drivers.

Allen Head Tools

You never know what kinds of fasteners you’ll need to tighten up in the many brands of window air conditioners out there. Some of them use larger Allen head screws to secure parts inside the case.

Universal Socket Set

We suggest the   Husky 16-Piece Universal Socket Wrench Set, Model 702200.  This comes with a handy holder to keep the wrench and sockets together. Plus, this set features most of the common socket sizes that you’ll find the most useful during typical air conditioner repairs.  You may also need a socket extender (sold separately) to reach those distant nuts and bolts.  But we’ve found this set to work well in virtually all circumstances.

Multi Meter for Fixing Noisy Window Air Conditioners

A meter comes in handy for checking correct line voltage and troubleshooting thermostats, micro switches, and fan motor windings.  But you need not spend an a lot of money on it, because you don’t need great reading precision when testing air conditioner parts.  We suggest pending no more than $50 for a meter used in HVAC repairs.  You’ll get the accuracy you need for this work, without having to worry too much over breaking a very expensive meter if you drop it.

HVAC Pressure Meter

In certain cases, the refrigerant pressure may be wrong. This can cause noisy compressor operation.  Yet unless you plan on fixing lots of loud air conditioners, you can usually get by without this tool.   Only buy one if you’ve tried everything else to lower the sounds, but the compressor still seems noisy.

White Lithium Spray Grease

Choose a product that has a very long straw, for reaching those recessed motor bearings within the air cooler. When fixing noisy window air conditioners, you need an applicator that reaches all places inside the unit.

Rubberized Weather Stripping

Used to fill in spaces in which metal vibrating against other metal can be a big source of noise.  You can “plug up” this vibration, by stuffing small pieces of this material in between the offending metal pieces.





Fixing Noisy Window Air Conditioners: Hints, Tips, Procedures, and Advice

Here are a couple of the tricks we’ve tried with decent success, to   fix  or  reduce window AC noise.

Install a High Quality Air Conditioner the Right Way

Unless you’ve bought a very well constructed and extra quiet window cooling unit, and took the pains to install it in accordance with low noise practices, air conditioners in general, tend to be a bit loud. Why?

Because most units have at least two motors (one for the indoor and outdoor fans, and the other is the refrigerant compressor).  Plus, some of the more costly models also feature water pumps (to draw out the condensed water).  Plus, they might have electronic air cleaners (for keeping dust, pollen, and other allergens at bay).  One great way to eliminate the need for ever fixing noisy window air conditioners, is to spend a little extra money for a unit designed with quiet in mind.

Check for Correct Line Voltage when Fixing Noisy Window Air Conditioners

AC motors such as those found in common air conditioners, can hum and buzz extra loudly when the line voltage is too low. Thus, when fixing noisy window air conditioners, solving any low voltage problems is quite important.  Not only can the right voltage fix the loud the air conditioner, but doing so likely prevents motor burnouts too.

To see if your voltage is too low, read the voltage at the outlet with a multi meter.  If too far below 110 or 220 volts, you may have other appliances on the same circuit, which can lower the value.  In that case, put the window air conditioner on its own circuit. We suggest that you place every window air condition on its own separate branch circuit if possible.

If the AC voltage is still too low, tell your power company.  They may be able to help.

But often the best approach in this situation, is to find an air conditioner that runs well on the lower voltage.  This search may take some doing.  But some work better on lower line voltages than others.  Check Consumer Reports, Redit, or other reputable sources for recommendations.





Be Sure the Wall is Solid

If the wall in which the window cooling unit vibrates too much, or is too wobbly, it may not be solid enough to give enough support to a window air conditioner.  Check this by knocking on the wall with a knuckle.  If even the gentlest of knocks sounds very loud or reverberates, the wall may actually amplify the AC sounds.  So you won’t gain much quieter ground when fixing noisy window air conditioners if your wall is rickety and weak.

To solve this issue, choose either brick or cement walls for your AC unit. Or, pick walls that offer thick wooden bases at window bottoms.  Also, blowing cellulose insulation inside the wall wall cavities may cut vibrations.  But the best answer to fix this type of air conditioner noise is to move it to a more suitable wall.

Grease All Brackets and Joints

Oil or grease any places where different pieces of metal in the air conditioner’s casing meet and could rub and bind. Use a thick oil or grease that can withstand heat, cold, and water without drying out, becoming too thin, or otherwise breaking down. One lubricant we used for fixing noisy window air conditioners, was white lithium grease.  And, we got awesome results.

But no oil or grease lasts forever.  It requires periodic re-application. So we “re lube” our air conditioners every other year.

When Fixing Noisy Window Air Conditioners, Be Sure to Oil Fan Bearings

Fans with dry bearings can squeal, start up too slowly, run hotter than need be, and can overheat and burn out.  Thus, routinely oiling with a long-tubed applicator helps them spin with less noise.  Oiling can also extend their lives too.

However, today’s bearings are pre-lubed. So they normally do not need more oil later.  In our experience, when they start squealing and squawking, oiling them solves the noise problem just briefly.  If they start squeaking too soon, you’ll probably have to replace the fan motor. Or at least, replace the entire bearing assemblies.

Clean and Vacuum Inside the Window Air Conditioner

Assure that none of the fan blades, louvers, vents, or air channels are caked with dirt and grime.  These deposits can add extra air flow noise through them.  Indeed, fixing noisy window air conditioners often involves a good and deep cleaning of the AC unit, both inside and out.

Clogged air passages can also result in whistling, roar, reduced cooling, and shorter appliance life.  So, keep it clean, for continued quietest running.

For stubborn dirt, use a steamer for best results. But avoid aiming the jet at electrical components inside, such as fan motor windings, starter capacitors, and switches.  Further, avoid shooting the steam near any wiring or plastic parts that might soften or melt even, in that heat.

Tighten All Screws

One very easy step in fixing noisy window air conditioners, is to tighten all screws, tap down rivets, and re drive nails.  Indeed, screws and fasteners that secure the air conditioner to the window frame may loosen and thus squeak when vibrating during normal operation.  Preferably, you drive screws into the thickest, most sound and solid areas of the window sash.  This provides a more rigid, less vibration transmitting backing.  Do not over tighten though, as you could strip the fasteners or crack the window frame.





Reinforce All Brackets and Joints when Fixing Noisy Window Air Conditioners

If seating the existing screws better in the previous step does not help enough, then consider adding your own fasteners.  We’ve done this successfully.

Hoping to reduce the need for lubricants mentioned above, we’ve reinforced the metal stand-off brackets in some of our air conditioners.  These better hold the fans and compressor in place. They suspend the fan motors and position the blades at the correct spot in front of the condenser coils.

Loose mounting that you find while fixing noisy window air conditions often causes tapping, pinging, and rattling due to motor vibrations shaking the loose pieces of adjoining metals.  So we drilled a single hole at the bases of each bracket where, it meets the case.  Then we drove a sheet metal screw into each one. As a final securing measure, we used thread lock on the screws to ensure their continued tightness.  This step showed the greatest noise-cutting effect.

While we still heard some vibration, the motors and mounting parts grew far less noisy.  So we keep a good supply of these fasteners around just for fixing noisy window air conditioners.

Replace Noise Isolating Grommets and Washers on the Compressor

The compressor inside is the largest source for the low-frequency hums, growls, buzzes, and raspy vibrations.  These seem to carry all through the house where window air conditioners are running.  So, manufacturers often suspend the compressor, atop these flexible washers to cut the noise.

For us, compressor vibration wasn’t as easy to solve as the air noises, squeals, and bangs. But we reduced hum by assuring that these washers have not rotted. When properly fastened, the bracket should hold the compressor firmly, but not tightly. In most window air conditioners, the compressor should “rock” a little due to the springiness of these flexible washers upon which it sits.  But you may not get adequate cushioning when the washers deteriorate or fall out.

Replace any Frayed or Loose Belts

Rubber fabric belts are often found in window air conditioners.  These transfer motion from an electric motor to the fan blades.  But failing belts here can create excess hissing, rubbing and squealing sounds, and thus, can add extra noise generated by your AC unit.

Replace the Window Air Conditioner

Sadly, the cheaper window units are often noisier, even when new. So they may not be suitable for bedrooms or other areas requiring near whisper quietness. Sometimes, especially in older cooling units, there’s just no toning them down, and your best bet is to replace them.

We’ve found that replacing these loud appliances with higher quality, newer models built for quieter operation, is usually the least aggravating and best overall fix.   But when that’s not an option, the above steps and tips often work well. Not perfect, mind you, but effective in many cases.   We’ve seen them work well in homes, apartments, trailers, and high rises. Hopefully, they’ll work for you as well.  Good luck.





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  5. How to Fix Honeywell WiFi Thermostat Connection Failure

Fixing Noisy Window Air Conditioner References

  1. What are air conditioners?    on Wikipedia
  2. Where to buy   Window Air Conditioners

Revision History

  • 2021-08-20: Shortened the internal links and tags lists.
  • 2020-05-24: Updated and optimized the text.
  • 2019-05-23: Added tags and links and tuned the targeting for ‘Fixing Noisy Window Air Conditioners’.
  • 2019-02-17: Added more subheadings and tags.
  • 2019-01-02: Added subheadings.
  • 2017-01-25: Updated tags list.
  • 2015-12-22: Added appropriate tags.
  • 2015-07-05: Added pictures.
  • 2015-03-02: Added the “Tools & Supplies Required” section, and fixed some typos.
  • 2014-12-30: Originally published.
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