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

Quieting Air Conditioner Window Unit

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 loud air conditioner window units. Indeed, we’ve installed these from five to twelve thousand BTUs at many apartments, homes, trailers, and even basements. We have been frustrated by the roaring fans, cycling compressors, snapping air cleaners within, and the window rattling as the installation loosens. We learned through the years how to reduce these sounds.  So here, we give our how-to instructions and hints for quieting air conditioner window units, that worked well.

Window AC units often thump, click, squeak, squeal, hum, whine, roar, and whir as their internal and external fans move air around.  E.g. They buzz, rattle, tap, tick, click, and vibrate.

Window air conditioners, installed in a free window, work well for addomg tp  the primary cooling HVAC system in the home. They’re cheap to buy (if not to operate).  But for quieting air conditioner window units you might need take on, as they age.  Even the best ones grower noisier over time.

Also, window air conditioners come in a wide range of cooling capacities.  In fact, the larger units even accept 220 volt power for best performance.  But they have their drawbacks too.  Their loud operation is perhaps the most annoying one.

Quieting Air Conditioner Window Unit: Warnings and Cautions

Turn Power Off

Before working inside an air conditioner window unit, unplug its power cord.  Otherwise, you could get a fatal electric shock. Especially likely in the 220-volt  units.

Watch your Fingers  !

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

Picture of the rear view of a typical window air conditioner, its hot side.
Typical window air conditioner unit, back view, hot side. Quieting air conditioner window unit.

Quieting Air Conditioner Window Unit:  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 numerous 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 organized, and features most of the common socket sizes that are most useful during typical air conditioner repairs.  You may also need a socket extender to reach those distant nuts and bolts.  But we’ve found this set to work well in virtually all circumstances.  A socket set that has many chucks is very useful when fixing noisy window air conditioners.


Needed to  verify correct line voltage and troubleshoot thermostats, micro switches, and fan motor windings.  however, you need not spend an exorbitant amount, as great reading precision is not required when testing air conditioner components.  We recommend spending no more than $50 for a meter used in HVAC repairs.  You’ll get the precision you need for this work, without having to worry too much over breaking the meter if you drop it.

HVAC Pressure Meter

In certain situations, the refigerant pressure may be incorrect, and can cause noisy compressor operation.  However, unless you plan on quieting lots of loud air conditioners, buying this tool is not absolutely necessary.  Only procure it if you’ve tried everything else to quiet things down, but the compressor still seems noisy.

White Lithium Spray Grease

Choose a product that features 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 can reach 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 source of noise, by stuffing small pieces of this material in between the offending metal pieces.

Picture of a Typical Window Air Conditioner, Front View, Cool Side.
Typical air conditioner window unit, front view, cool side. Quieting air conditioner window unit.

Quieting Air Conditioner Window Unit: Hints, Tips, Routines, and Advice

Here are a couple of the tricks we’ve attempted with moderate success, to   fix  or  reduce the electric heater noise. Note that these procedures apply only to convection type electric baseboard heaters, as these tend to exhibit lower surface temperatures than the hotter, radiant units.  Do not use lubricants on or near any glowing-type heating elements found in radiant heat sources.

Be Sure Supporting Wall is Solid

If the wall in which the window cooling unit vibrates too much is wobbly, it may not be solid enough.  That is, it may not give enough support to an operating air conditioner.  Check this by knocking on the wall.  If even the lightest of knocks sounds very loud, the wall may amplify the AC sounds.  So you won’t gain much  ground if your wall is rickety and weak.

To solve this issue, choose either brick or cement walls for your AC window unit. Or, pick walls that offer thick wooden bases at window bases.  Also, blowing insulation into wall cavities may lower vibrations.  But the best answer for this is to move the window unit to a higher mass wall.

Check for Correct Line Voltage

AC motors such as those found in common window air conditioners, can hum and buzz loudly when the volts are too low. When trying to quiet these units, you should address any low line voltage conditions. Very important. Not only can the right voltage quiet the air conditioner. But it likely keeps the motors from burning out as well.

To see if your voltage is too low, read the voltage at the outlet with a multimeter.  If too far below 110 or 220 volts, you may have other appliances on the same circuit, which can lower the reading.  In that case, move the window air conditioner unit on its own circuit.

If the AC voltage is still too low, mention this to your power company.  They may be able to solve that problem. Yet often the best approach in this situation, is to find a window unit that runs well on 90 to 105 volts.

Install a High Quality Window Air Conditioner Unit the Right Way

Unless you’ve bought a very well built and extra quiet window cooling unit, and took the pains to install it following noise quieting practices.  Air conditioners in general, like those for a window, are often loud. Why?

Most units feature at least two motors (one for the indoor and outdoor fans, and the other is the refrigerant compressor).  Plus, some of the better models also have water pumps.  These draw out the condensed water.  Some have electronic air cleaners that keep dust, pollen, and other allergens at bay.  One great way to eliminate the need to for quieting air conditioner window units, is to spend a little more cash on a unit built to be quiet.

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 holds up well in heat, cold, and water. It should not dry out, get too thin, or otherwise break down. We use white lithium grease and get impressive quieting.

But no oil or grease will do the job forever.  Grease needs periodic re-application. We re lube our air conditioner window units every year or two.

Oil Fan Bearings

Fans with dry bearings can squeal, be slow to start up, and overheat and burn out.  So routinely oiling with a long-tubed applicator helps them rotate more smoothly and quietly.  Oiling can also extend their lives considerably too. Use a high temperature silicone based oil on fan bearings.

Note though that today’s motor bearings are pre-lubed. So they normally do not need oil later.  We find that when they start squealing and squawking, oiling them quiets them only briefly.  If they start squeaking too soon, you must replace the fan motor. Or at the very least, replace the bearings.

Clean and Vacuum Inside the Window Air Conditioner Unit

Assure that none of the fan blades, louvers, vents, or air channels have dirt and grime.  Dirt build up can increase air flow noise through them.  Clogged air passages can also cause whistle, roar, reduced cooling power, and shorter air conditioner life. Indeed, quieting an air conditioner window unit often involves a deep cleaning, both inside and out.  Keep it clean, for continued quietest operation.

For stubborn dirt, use a steamer.  But avoid aiming the jet at electrical components inside.  E.g. Fan motor windings, starter capacitors, and switches.  Avoid also shooting the steam near any wiring or plastic parts.

Tighten All Screws

One very easy step in quieting window air conditioner units, 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.

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.  You could strip the fasteners or crack the window frame.  So be careful.

Tighten All Brackets and Joints

If seating the existing screws better in the last step helps not enough, then add your own fasteners.  We do this successfully now and then.

Hoping to reduce the need for lubricants mentioned above, we tighten the metal stand-off brackets in some of our window units.  These hold the fans and compressor in place. Plus, they suspend the fan motors and position the blades at the correct spot in front of condenser coils.

Loose mounting often causes tapping, pinging, and rattling due to motor vibrations. This shakes the loose pieces of adjoining metals, and adds extra noise.  So we drill a single hole at the bases of each bracket where, it meets the surrounding case.  Then we put a sheet metal screw into each one. As a final measure, we used thread lock on the screws. This keeps them tight for years.

While we still hear some vibration, the motors and mounting parts get far quieter than before the extra sheet metal screws.  So we keep a good supply of these fasteners around just for quieting air conditioner window units.

Replace Rubber Grommets and Washers on the Compressor

The compressor inside is the largest source for the low-frequency hums, growls, and raspy buzzes.  These sounds carry all through the house.  So, manufacturers often sit the compressor, atop these flexible washers

This compressor sound problem isn’t as easy to quiet as the air noises, squeals, and bangs. But we often reduce hum by checking that these washers have not rotted. When rightly fastened, the bracket should hold the compressor firmly, but not tightly. In most window units, the compressor should “rock” a little due to the springiness in these soft washers.  But you may not get enough cushioning when these washers decompose and fall out.

Replace any Frayed or Loose Belts

We often find rubber belts in window air conditioners.  These transfer motion from the motor to fan blades.  But failing belts here can cause excess hissing, rubbing and squealing sounds. They thus, can add markedly to the noise your your AC unit makes.

Replace the Window Air Conditioner Unit

Sadly, the cheaper window units are noisier. So, they may not work well in bedrooms or other areas needing quiet. Sometimes in older cooling units, there’s just no toning them down.  In these, your best bet is to just get new ones.

We find while quieting window air conditioner units, that replacing them with higher quality, newer models, is usually the best long term solution.   But when buying new not an option, the above steps and tips prove to work.  Not perfect, mind you.  But they do quiet a noisy air conditioner. Hopefully, they’ll work for you as well.  Good luck.

Related Posts to Quieting Air Conditioner Window Unit

    1. Fixing Noisy Portable Fan Heaters
    2. Electric Baseboard Heater Noise, How to Fix
    3. Blaster Graphite Dry Lube Spray Review
    4. Fixing Squeaky Wooden Glider Rocking Chairs Tips
    5. Hard Drive Making Clicking Noise Fix

Quieting Air Conditioner Window Unit References

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

Diary of Revisions

    • 2019-04-01: First released.