Stop the Noise! What Your Loud Air Conditioner is Telling You!

air conditioner

In Australia we love our air conditioners. They make it possible for us to live, comfortably, in one of the hottest places on Earth. Air conditioners keep our rooms wonderfully cool while remaining reasonably quiet. But when your air conditioner starts to get noisy or louder than usual, it is almost definitely a sign that something is wrong.

A little noise when your air conditioner starts is normal. An air conditioner is a large machine with a great many moving parts – there will always be some noise involved. After all, if it is dead silent it usually means the unit is off or completely useless. Further, older units are more likely to make a louder noise than newer units that have the benefit of more modern designs.

There are a lot of reasons for a noisy air conditioner, depending on the type of unit. But the universal truth is that a loud or newly noisy air conditioner should not be ignored. An increase in noise is a sign that something is in the process of going wrong or already has gone wrong. And the longer you leave it, the more damaged and dangerous your unit can become. So join us as we discuss the top 10 noises your air conditioner might make and what they can mean.


Complaints of rattling are one of the most common issues with air condition units. It is also the one with the most varied causes. Rattling from the AC unit itself can mean that the fan might be loose or need cleaning. Rattling can also occur if the fan blades have somehow become bent and are touching the inside of the unit or fan casing. Further, rattling from inside a unit can be caused by small children placing toys and other foreign objects into the unit itself!

When our air conditioners run, they subtly vibrate. Over time, this vibration can cause bolts or panels on the unit to come loose and begin to rattle. This same vibration can also cause the rubber feet on the compressor unit to crack or disintegrate, causing the compressor to become unbalanced and rattle. An aging compressor motor can also create a rattling noise – an indication that it needs to be replaced.

Finally, rattling from outside and around the air conditioning unit could point to issues with the ductwork. This includes loose panels or ducts, debris and foreign objects that have fallen into the ducts, and even animals/pests that have fallen into (or are living in) the ductwork.air conditioner


Humming is another common complaint when it comes to noisy air conditioning units. Now, most AC units will hum a little as part of their normal process. But excessive humming sounds can indicate bigger issues. Minor humming issues can be caused by a poorly cleaned unit, where the coil fins have been clogged by dust and debris – even large foreign objects. Bent coil fans – which can occur in very clogged units – make a humming noise as they brush against the inside casing of the unit.

While the above are less serious issues – and can be easily prevented with cleaning – there are more serious issues associated with humming. While AC units are heavily lubricated at construction, this lubrication can eventually waste away. A loudly humming AC unit may be in need of more lubrication. Finally, humming can indicate that the starting capacitor is failing – something that will need the quick attention of a professional.


Squeaking is yet a third common issue reported from noisy air conditioners. Squeaks can be caused, like rattling and humming, from a build up of dirt and debris in your AC unit. This is why it is important to keep your air conditioning unit clean. Squeaking can also be caused by minor bends or damage to the fan. A squeaking fan motor can indicate that it needs cleaning or lubrication, but should also be checked by a professional to ensure that there are no larger issues at play.


Grinding is a more concerning noise and it can indicate that something is about to go very wrong – if it has not already. This noise can be caused by the lubrication around the dual shaft motor breaking down. This indicates it requires replacement. Further, grinding could mean that a fan motor bearing – or other essential bearing – is worn or has failed. This is a serious issue that can cause further damage to the unit. It must be investigated quickly by an air conditioning professional.

Clicking and Popping

Clicking and popping are also noises that are normal in air conditioning units. These noises generally occur when turning the unit on and off, indicating that the air is kicking on and off. However repetitive pops or clicks are not normal. This could indicate a defective relay that needs repair or replacement. Clicking noises can also be an indication of a failing thermostat or defective control system. Finally, popping noises can indicate aging ductwork that pops as the air cuts on and off. If your unit is making repetitive popping and clicking noises, you should seek a repair professional immediately.air conditioner

Squealing and Screaming

Some of the most alarming noises your air conditioning unit can make are screaming and squealing noises. If you have heard this sound, then we are sure you realise that something is wrong with your unit. Screaming and squealing noises can indicate a motor belt is slipping or has slipped, that the bearings on the condenser have worn down, or that the compressor is failing. These serious issues need to be addressed quickly.

Buzzing and Crackling

Buzzing and crackling noises might not seem as serious as an AC unit that makes screaming or squealing noises. However, buzzing and crackling sounds can be the sign of serious issues with your air conditioner’s electrical workings. These noises can indicate arcing electricity or a malfunctioning compressor.

Further, a unit that has become frozen due to refrigerant leaks can also buzz as it attempts to work. These are all serious problems and need the attention of an expert repairman immediately.


Our final disconcerting air conditioner noise is perhaps one of the most sinister. A hissing air conditioner can indicate a minor issue – such as a return air leak. However, an AC unit can also hiss if it is leaking refrigerant – sometimes known as HFC (hydrofluorocarbons), HCFC (hydrochlorofluorocarbons) or CFCs (chlorofluorocarbons). These chemicals are highly toxic with over exposure occurring at only 11% concentration. The refrigerant displaces air and can cause asphyxiation in small spaces, like apartments. Symptoms include dizziness, loss of concentration, central nervous system depression and cardiac arrhythmia.carbon monoxide john's refair

Due to this highly toxic risk, any hissing air conditioner must be immediately turned off and a highly qualified air conditioning repairman called.

Air conditioners are invaluable in helping us lead comfortable lives all year round. So it is only right that we ensure we keep our units maintained and regularly serviced. Like everything in our homes, air conditioners need cleaning to combat the build up of dust, hair, and debris. Your unit should also be regularly serviced, at least once a year. Booking in a yearly check up with John’s Refair means you have the peace of mind that your system will be running perfectly all year round. Call us today to find out more about our maintenance services!