How To Quiet A Noisy Window Air Conditioner (5-Step Guide)

There are few things in life that are more irritating than persistent noises from household appliances that shouldn’t be making said noises.

Window air conditioners are regular offenders when it comes to unwanted noise in the home.

Luckily most of these rattles, squeaks, thuds and bumps that plague window air conditioning units can be fixed by anybody with the time and patience to do so, and, of course, a basic set of tools found in most households.

In this proHVACinfo guide, we’ll be learning about:

  • What You Need To Know About Noisy Window Air Conditioners (common noise culprits)
  • Tools And Supplies You’ll Need To Quiet A Noisy Air Conditioner (get the right tools amd avoid damaging your AC!)
  • How To Quiet A Noisy Window Air Conditioner (5-step guide)

And much more!

What You Need To Know About Noisy Window Air Conditioners

There are many reasons why your window air conditioner could be making unusual, or irritating noises.

First, let’s remember that these are seasonal appliances, meaning that they get picked up, moved around, and generally handled much more than a static, permanent AC unit.

These knocks and bumps can cause components to come loose, and with the vibration that comes with normal operation, extra noises can start to occur.

Additionally, these units are much closer to your living spaces than a fixed air conditioning system would ever be.

Any change in noise will be much more noticeable as a consequence.

Not all noises are caused by the same problems, of course.

In fact, the particular type of noise you’re encountering can tell you a lot about the issue you’re having, and with that diagnosis, you should be able to make a repair.

Some of the underlying causes of noisy window air conditioners include:

Improper Installation

If the unit isn’t installed in the correct manner, this can cause excess vibration, which alone can cause noise, but left unchecked can cause components to rattle loose and create further problems.


If debris has entered the unit housing while the fan has been running and impacted a blade, this could cause deformations, chips, cracks, and bends that will cause an imbalance.

When a fan turns at high speed with an imbalance, it will vibrate, and this could be mild or severe.

There is also the possibility that the fan is continuously contacting either the housing, or debris that is stuck inside.

Fan Bearings

Especially if the noises are squeaky or screechy, your fan bearing could be to blame.

The fan bearing is responsible for smooth rotation of the fan blades, and if it has rusted, or otherwise dried out, the friction will almost certainly create noise.

Fan Motors

The fan motor is probably the hardest working piece of the system, which is why it’s also one of the most likely components to break down, and cause noise.

Your window AC fan motor’s bushings will erode over time, resulting in squeaking, or even roaring noises.

If the fan motor is to blame, 9 times out of 10 you’ll need to do a full replacement, as they are typically sealed units that cannot be repaired.

Spring Clamps

Window air conditioning units usually feature two sets of fan blades, one to draw air in, and one to vent off warm air from your home.

Because most window AC systems use a dual shaft motor, both fans are attached to the same motor using a spring clamp.

If the spring clamp is in any way damaged or worn out through years of service, the fan blades can become loose, which can cause noises from vibration as well and knocks and clanging.

Trapped Debris

Window air conditioners are very much exposed to the elements, and if they’re installed anywhere near a tree, there’s a good chance that sticks, twigs and leaves will end up inside the housing at some point.

When this happens, they can come into contact with moving parts like the fans, and any number of unusual noises will occur.

Tools And Supplies You’ll Need For Cleaning A Furnace Flame Sensor

Quieting your noisy window air conditioner doesn’t require a vast arsenal of tools, spares and equipment. To remove, dismantle, and repair your unit, you’ll need the following:

1.  A ratcheting screwdriver set – This kit from Craftsman is our number one recommendation. It’s very well made, feature packed, and comes with a range of Phillips, flathead, and Torx bits. No matter the brand or model of your window AC unit, you’ll almost certainly have what you need to dismantle, repair, and reassemble in this kit.

2.  A coil cleaning brush – Many noise issues are caused by dirt and debris stuck inside the unit, cleaning out the coils is very important. Not only that, but taking care of this will also help you get your window AC unit back to peak operation.

3.  Coil Cleaning Foam – Coil cleaning foam really helps speed up the cleaning process. Simply spray on, leave it to work for about 3 minutes (but no longer than 5), then rinse it off. With cleaning foam, your brush should make light work of any remaining dirt.

4.  Fin Comb – You’ll use these to straighten the coil fins in your AC (more on that below). The coil fins are very delicate, and if you bump them, they can very easily bend. For that reason, we recommend using this specialized tool.

5.  Condensate pan treatment tablets – While your unit is stripped down, place these tablets in the collection tray to prevent mold or algae developing in the standing water.

6.   Light Machine Oil – You’ll use this to lubricate your AC’s bearings and other moving parts. Note, you should never use all purpose lubricants like WD-40 on an air conditioning unit.

If the problem is due to a worn component, you’ll need to identify the make and model of your window air conditioner and research the replacement part accordingly.

Fortunately, these are simple devices, with most parts only being held in by a screw or two, so components are easy to remove and replace.

How To Quiet A Noisy Window Air Conditioner (5 Steps)

Before you start – Safety First! When the cover is off your window air conditioning unit you’ll be exposed to high RPM moving parts, and potentially significant voltage.

Make sure that all work is conducted with the unit unplugged from the outlet, and if you do need to plug it in to test while the cover is off, you stand well back and keep your hands clear.

Step 1: Ensure that the until is securely installed

Before breaking things down, try the simple option first.

Ensure that the window you install the unit in is on a solid wall, not in a partition or other hollow area.

The brackets should be tight, with absolutely no wiggle room. If you discover that any of these parts are loose, tighten them and turn on the unit to see if the situation improves.

You also need to make sure that any putty or weather sealing hasn’t dried out. If it has, it will have become hard, and won’t provide any vibration damping, leading to noise and further damage to the unit.

Step 2: Check inside the unit

Remove the window air conditioning unit from its bracket. It’s a good idea to have somebody help you with this to avoid dropping it.

The front panel will either be held on with screws or tabs. If it’s held on with crews, loosen them to remove.

If it’s held on with tabs, use a flat head screwdriver to depress the tabs, and slide the cover off.

The top of the housing will almost certainly be held down with screws. Loosen those, and slide the cover off the top

Right now, you should check for obvious debris. Pick out any leaves, sticks, plastic, or anything else that has found its way inside the unit.

This is also a good time to clean the fan blades and condenser coils.

To do so, spray the condenser coil fins with the foam, and leave for three minutes before rinsing, then, take your brush and carefully scrub inside the fins.

If you encounter damaged fins, or damage any yourself while cleaning, the fin straightening tool should pull those bends right out.

Place your condensate pan treatment tablets into the tray now.

To clean the fan blades, we like to recommend Bar Keepers Friend. It gets metal shining like new and requires very little effort.

Step 3: Check that the fan blades are intact and that they rotate easily.

If there was no obvious debris causing issues, or you suspect that the debris caused further damage, then it’s time to check the fans, fan motor and fan bearings.

Perform a visual inspection of the fan blades, ensuring that they are all uniform, with no cracks, chips, dents or bends.

If any of these conditions exist you’ll need to replace that set of fan blades.

Next, try to turn the fans by hand, they should rotate without much, if any resistance, and they certainly should not squeak or scrape.

Noise here indicates that the fan is either coming into contact with another component, or from a bad fan bearing or fan motor.

It should be fairly easy to deduce which area the noise is coming from when you’re turning the fans.

If the fan is coming into contact with debris, simply remove the obstruction.

If it’s contacting another component, ensure that the fan has not come loose, and if it has, reset it to the correct position and tighten its securing screws or clamps.

If it’s a spring clamp, replace it if necessary.

If you rule out the fan coming into contact with anything, then apply a drop or two of light machine oil to the bearing and the fan motor shaft and turn the blades to work it in.

Avoid using excessive amounts of oil, and keep all lubricants away from electrical, rubber, or plastic components to avoid damage.

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.

Step 4: Tighten any loose components.

While the unit is open (and clean), look around for any other loose components like nuts, screws, belts or anything else that could possibly shake free. Tighten up any screws, and if fan belts appear to be worn, replace them.

Loose components may not have anything at all to do with your noisy fan, but regardless, if you discover them, it’s a good idea to tighten them up to prevent any new issues developing later on.

Step 5: Reassemble and reinstall

Follow the dismantling steps in reverse to reinstall your window air conditioning unit. Let it run for a few minutes to see if the issues have been resolved.

In the event that one of these simple fixes did not solve the problem, it may be time to consider replacing the entire unit, as anything else might be indicative of a major issue, which may cost almost as much to repair as a new air conditioner.

Stephen Marks

Stephen Marks

Stephen is an HVAC and home-repair enthusiast. He's here to answer any of your questions about HVAC!

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Stephen Marks

Stephen Marks

Stephen is an HVAC and home-repair enthusiast. He's here to answer any of your questions about HVAC!

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