Portable AC Is Making Noise? Here Is Why

For a few fall, winter, and spring months you might have forgotten that you needed a portable air conditioner.

Next summer, however, you switch it on only to find that it’s making the worst noises.

How can you tell if that noise coming from your portable AC is bad?

Depending on the AC unit model, noise it makes can be caused from any number of internal issues that should be addressed immediately. Common disturbances are buzzes, banging, hissing, rattling, or humming, to name a few. Observing the distinct noise type is important to diagnose the problem.  

Below, we’ll discuss where those sounds are coming from, what they mean, and how to repair them.

Portable AC Making a Banging Sound

Most portable air conditioner owners complain of their unit suddenly starting to bang or rattle without warning.

This is often a sign of a serious, costly, defect like a broken fan or compressor. It could also mean loose screws and bolts, the unit is unstable, or a piston has broken.

On the other hand, it could be something as simple as debris that has found its way into your unit.

This is an easy fix. Simply remove whatever it is out with your hand, trowel, or use a vacuum. If the noise persists, then contact your local appliance technician.

Buzzing Sound Coming from Portable AC

If you hear a buzzing sound or “whir” from your portable air conditioning unit it could be the result of one or all of the following concerns:

  • Having a faulty connector or contactor switch can cause your portable AC unit to buzz, as well as prevent it from powering on 
  • The capacitor may need replacing if your AC stutters when turned on before eventually turning it off. A bad capacitor is a common problem and will cause the unit to buzz or click
  • A worn compressor, the part that pressurizes and cools your unit’s refrigerant, will also cause the AC to buzz 

Portable AC Squealing

A rarely used portable AC unit that squeals when you turn it on may signal something is wrong, or, perhaps, nothing at all.

The worst case is replacing the condenser fan blower motor. Do not attempt to fix this on your own.

You will likely make matters worse, thereby increasing the costs incurred by hiring a professional technician. 

Hopefully, you haven’t used your portable AC for a while, and, like most neglected machinery, it takes a moment to “warm up” before working properly again. 

Colder months take a toll on your unit’s lubricants.

Squealing may mean it needs time to unthaw. The noise should ease after a while. If the problem persists longer than a few hours, contact a trained appliance pro.  

Portable AC Is Hissing

There’s nothing good about a hissing portable AC. 

It’s possible that refrigerant (aka, Freon), the liquid gas that cools the warm air, is leaking from the compressor and should be switched out before ruining the AC unit.  

Image Credit : hackaday.com

The following can happen if your AC compressor is leaking:

  • It takes longer than normal to cool your home/room
  • Vents continually blow warm air 
  • Electricity bills increase due to malfunctioning AC wasting energy 
  • Refrigerant line is iced over 

If any of these applies to your portable AC unit, only a certified appliance professional can handle and refill toxic refrigerants (required by law) and check leaks with specialized tools.

Portable AC Clicking When On

Upon turning on your portable AC unit always makes an audible clicking sound could indicate that your thermostat, control board, or capacitor is not working properly. 

If the clicking happens only when you either turn the unit on or off don’t panic, but do keep an open ear.

If the noise persists before turning the unit off there could be a compressor start relay.

Portable AC Pulsing Noise

Does your portable AC unit pulsate between loud and soft while on? If so, the source may be from a compressor that is not insulated properly. 

Oftentimes, the surface that the compressor rests on will pulsate or buzz while the unit is on.

Another cause might be that the refrigerant line is vibrating against the wall. Try either changing the surface or moving the hose.   

Pulsating noises don’t necessarily indicate something serious unless you hear a metallic sound. This could mean that your unit’s fan has come loose.

You probably could fix it on your own with a screwdriver and pliers, but it is best to call a professional

Whistling Noise From Portable AC

That whistling coming from your portable AC unit isn’t playing a tune for you, but is probably having trouble breathing!

Just like a clogged nose, it is not inhaling enough air into its return vents. The result is forced air trying to escape under pressure, hence the whistling. 

The good news is that this is not a serious problem and can be alleviated by:

  • Cleaning the filters
  • Replacing filters
  • Unblocking air return vents
  • Opening dampers 

While you’re at it, check the unit’s ducts for leaks. A cracked duct allows air to flow through the openings, thereby creating a whistling sound.

You could be whistling at a high repair bill if your system struggles to breathe longer than necessary. So, save yourself the hassle and fix it today.

Shaking and Rattling Noise From Portable AC

Your portable AC unit is a machine and like most things mechanical, parts fail after long use and will start to shake, rattle, and roll loose when turned on (sometimes after powering off).

Unfortunately, this is a sign that something is wrong with either the motor and/or ducts.

Before going down that frightening scenario, check to be sure that the panels of your portable air conditioning unit are screwed tightly and secured.

If not, grab a screwdriver, pliers, or whatever tool required to fix the problem yourself.  

Seek help from a certified appliance technician if the unit is mounted to a more solid base like concrete or steel. They will have the tools for heavy-duty bases.

Shaking, rattling, and rolling can also be caused by:

  • Broken motor. It is the most active AC part and will eventually wear out. When it goes, expect the other internal parts to shake, rattle, and roll
  • Dirt, leaves, twigs, etc. If your AC should become obstructed by any foreign objects they will be blown about inside and cause it to rattle. Clear debris promptly to avoid damaging internal parts
  • Fan not aligned. A wobbling fan will hit its casing and create a rattling sound. If you cannot fix yourself, please call an appliance pro.

Sound Advice Concerning Your Portable AC

Not all strange noises your AC makes mean that something must wrong with it! Sometimes, a solution is simple.

For instance, there could be a loose thingamabob or doohickey that can easily be fixed by you (DIY), saving the cost of a repair diagnosis. 

Some HVAC professional websites will offer their advice to you for free. They may even help you solve the problem over the phone!

But when it comes down to one or more of the serious issues mentioned above, be sure to schedule an in-home inspection with your local technician.  

They will quickly and accurately identify the problem source, suggest a repair plan, and leave the rest up to you.

If their price seems too high or they are overbooked, there are many appliance technicians in your area from which to choose.

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