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What to do when your air conditioning makes a strange noise

Air conditioning making a strange noise

If your air conditioning begins to make an unusual noise, it could be a sign that your unit is faulty, may need cleaning or replacing. Analysing the type of sound can indicate what exactly is wrong with your AC system so that you can notify your maintenance team and resolve the issue as quickly as possible.

Flowing water

The sound of flowing water in your system is quite common and does not indicate a fault with your air conditioning unit. It is simply the outdoor unit going into defrost operation. It is advised to leave your unit for a few minutes and the noise should cease.


If you hear a buzzing noise from your unit, this can be attributed to the flap within the system and is no cause for concern. However, if the volume increases to a loud and irritating level, this could be an indicator that there’s a fault within your compressor or perhaps a loose component.


A hissing or crackling noise is typically the release of ventilated air, sometimes referred to as streamer discharge. This is a common occurrence.


When the electric component or refrigerant control valve in your system operates, it can produce a clicking noise. If the system produces a clicking noise when not in operation, it’s likely there is an electrical problem within the unit.


A slow and steady rumbling or soft hum noise is common with air conditioning units, especially when in ventilation (fan) mode.


In well-sealed rooms that are closed off, outdoor air can enter the drain hose, especially in strong winds and bad weather conditions outside. This then causes a bubbling sound. If these conditions do not match yours, it may be that you have a refrigerant leak.

Abnormal noise

If your air conditioning system is making a strange noise during operation that isn’t mentioned above, you should turn off your system and contact your manufacturer or local maintenance team to ensure that the system is safe.

Any issues and sounds with your system are best handled by a professional engineer, so do get in touch with your supplier or maintenance contractor to minimise risk. With a regular maintenance contract, you can greatly reduce the risk of AC unit fault and ensure an efficient system for your premises.

For more information on TEK’s air conditioning servicing in Bristol, please get in touch with the team by calling us on 0117 952 3355 or fill in our contact form and we will reply shortly.