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

Fixing Noisy Window Air Conditioners

Anyone living in warmer climates probably has delt with this problem of fixing noisy window air conditioners. Indeed, we’ve installed units from five to twelve thousand BTUs in apartments, homes, trailers, and even basements. And all the noises they make has frustrated us.  Every noise from roaring fans and cycling compressors, to snapping air cleaners, and rattling windows. But we investigated and found many solutions for this over the years.  So 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 they operate. They can buzz and vibrate a lot as well. Then, when they turn OFF, window air conditioners often thump.  Then they tick and pop as their metal parts cool off (or warm up).

Air conditioners, installed in a free window, work well for supplementing the primary HVAC system in the home. They’re cheap to buy (if not to operate).  Plus, you can move them from room to room where you need them. But you might need to work on them 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. Some air conditioners use larger Allen head screws to secure parts inside the case. But others use smaller ones.

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 while making these 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. Why not? Because you don’t need great precision for this work.  The cheapest meters will do, so long as they can read up to 250 volts AC.  We suggest spending no more than $50 for a meter used in HVAC repairs.  You’ll get the accuracy you need. And you won’t have to worry much over breaking a pricey 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 lubricating your 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 get a higher notch model and install it correctly, air conditioners, tend to be normally loud. Why?

Well, most units have at least two motors. One is for the indoor and outdoor fans, and the other is the compressor.  Plus, some of the more costly models feature water pumps to get rid of condensation.  Furthermore, they might have electronic air cleaners. These keep dust, pollen, and other allergens from circulating through your home.  So with all these components feeding the din, a well-built unit is essential. Indeed one great way to address the noise, is to buy a unit designed with quiet operation in mind.

Check for Correct Line Voltage when Fixing Noisy Window Air Conditioners

AC motors such as those in common air conditioners, can hum and buzz excessively with low line voltage. Thus, fixing these problems is important.  Not only can the right voltage fix the loud the air conditioner. But doing so likely prevents motor burnouts as well.

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, then this can have many causes. You may have other appliances running 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 where possible.

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

But often the best approach here, 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 good sources for suggestions.





Be Sure the Wall is Solid

If the wall vibrates too much, or wobbles, it may not be rigid enough to support a window air conditioner.  So check this by knocking on the wall. If even the gentlest of knocks sounds very loud, the wall may actually amplify the noise.  So you likely won’t cut the noise 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 way to fix this type of noise is to move the unit to a more solid wall.

Grease All Brackets and Joints

Lubricate any places where different pieces of metal in the case meet and could rub and bind. Use a thick oil or grease that withstands heat, cold, and water. It should neither dry out, get too thin, or otherwise break down. One lubricant we often use for fixing noisy ACs, is white lithium grease.  And, we get 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, grind, or buzz. Plus they can start up too slowly, run hotter than spec, and so, can overheat and burn out.  Thus, routinely oiling helps them spin with less noise and wear.  It can also extend their lives too since oil generally reduces wearing.

However, today’s bearings come with lube already on them. 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 have dirt and grime. These deposits can add extra air noise. Indeed, fixing noisy window air conditioners often involves a good and deep cleaning of the unit.

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 is to tighten all screws, tap down rivets, and re drive nails.  Indeed, screws that hold the air conditioner in the window may loosen. Then they squeak as the unit vibrates and shakes as it runs. So it’s very important that they stay tight.

Now to fix this noise, you drive screws into the thickest, most sound and solid areas of the window sash.  This provides a more rigid backing less prone to noise. But do not over tighten the screws, as you could strip them 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, we reinforced the metal stand-off brackets in some of our units.  These better hold the fans and compressor in place. Plus they help suspend the fan motors, and position the blades at the correct spot in front of the coils.

Loose mounting often causes tapping, pinging, and rattling, This comes from  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. We then used thread lock on the screws to prevent loosening.  This step gave 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 these noisy 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. Why? This cuts down on the noise due to the springiness of these flexible washers upon which it sits.  But you may not get enough cushioning when the washers degrade or fall out.

Replace any Frayed or Loose Belts

Rubber fabric belts you often find 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. Thus, they can add extra noise to your air conditioner.

Replace the 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 find that replacing these loud appliances with better quality models built for quieter operation, is usually the best fix.   But when that’s not an option, the above tips often work well. Not perfect, mind you. But they can be effective in many cases.   We’ve seen them work well in homes, apartments, trailers, and high rises. So hopefully, they’ll work for you as well.

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References

    1. Where to buy Window Air Conditioners