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Common Air Conditioner Noises and the Problems They Indicate

air conditioner

The most current energy-efficient central air conditioning systems use two-stage or variable speed motors designed to make little or no noise. 

If you detect a loud sound coming from your air conditioning unit, this could be an indication of a problem within your unit. These noises are generally a sign that it is time to schedule an aircon service.

This article will run you through some noises from your air conditioning unit you should not overlook. These noises may even help you determine the problem with your system.

Broken Compressor Causing Banging Noises

If your air conditioning unit produces a pounding noise, this might indicate a compressor problem. This component is designed to deliver refrigerant to various sections of your home’s HVAC system to eliminate excess heat. 

It is relatively common for parts to become loose inside the compressor when your ducted air conditioning system approaches the middle or close of its lifecycle.

Malfunctioning Fan Motors Causing Screeching Sounds

The most typical cause of an air conditioner shrieking noise is a faulty fan motor in the outside condenser unit. A fan in the air conditioning system attached to your home is meant to extract heat from the condenser. 

If your air conditioner is screeching, it might be due to a problem with the fan motor. A faulty motor in the condenser system’s compressor might also generate this sound.

Humming Noises from a Defective Contactor Relay Switch

Because of a faulty contactor relay switch, you may begin to hear a buzzing noise within your air conditioner. When it gets input from your thermostat, this component activates the outside condenser unit. 

Unfortunately, you will be unable to switch on your air conditioning system until a professional technician resolves the problem. Do not disregard electrical issues in your system. Doing so will lead to severe damage to your ducted air conditioning system, and it entails costly repairs.

Rattling Noises from Some Dirt or Leaves in Your Outdoor Unit

In the best-case scenario, stray twigs, dust, or foliage in your exterior condenser unit are causing your air conditioner to rattle. The simplest solution is to dismantle the device and remove these elements. 

In the worst event, this air conditioning unit sound might be caused by a faulty electrical component in your system. If you find a defective contactor, you should address it as quickly as possible to avoid causing harm to your central air conditioner’s compressor.

Clicking Sounds of a Malfunctioning Thermostat

While hearing a clicking noise at the start or end of your cooling cycles is normal, hearing a consistent clicking noise from your air conditioner is not. This sort of noise might be an indication of a faulty thermostat. 

Hissing Noises from an Air Duct Leak

If your air conditioner is hissing, it might indicate a mild to significant air duct leak in your home. This sound might be due to a faulty expansion valve or an air filter that is incompatible with your system.


If you are experiencing one of these noises in your air conditioner or any other strange or peculiar noises, you should contact a professional air conditioning repair service. They can complete a diagnostic review of your central air conditioning system. Otherwise, you risk facing extensive damage to your air conditioning system or the need to replace it prematurely.

Are you looking for air conditioning services in Sydney? Roberts Air Conditioning specialises in air conditioning installation, maintenance, and repairs. Book a free consultation today!