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8 Most Common Types Of Aircon Unit Noises

Is your window aircon unit making an unusual noise? Is it disturbing the silent ambiance of your quiet room in the middle of the night?

With the development of sound-dampening technology, as well as the two-stage (variable speed) compressors to keep noise levels below 55 dB, our aircon units are now quieter than ever.

If you notice that your aircon unit is making weird noises, it is likely that there is a singular internal issue or multiple faulty parts clashing together inside the aircon unit. Of course, some sounds might mean nothing. However, it is better to know what the most common sounds are and what they mean for your aircon unit.

Read on to find out the 8 most common types of aircon unit noises and help diagnose any potential issues with your aircon unit.

Rattling Noises

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aircon installation

Well, the condenser is the outdoor portion of an aircon unit that either releases or collects heat. With exposure to dirt or tiny particles, it can end up accumulating debris which causes the unit to produce a rattling sound. To solve this, you can simply disassemble the unit to remove this debris. Again, this is why 338 Aircon emphasizes the importance of regular aircon cleaning. Read here for 5 Creative DIY ways to clean your aircon units.

If you hear rattling noises despite cleaning your aircon unit regularly, you are recommended to get your professional aircon servicing company to have your aircon unit checked. Otherwise, a malfunctioning contactor can cause damage to the compressor.

Banging Noises

Banging is typically an absolute indication of loose or broken parts inside the compressor. When the components become unfastened in the compressor, they will hit the compressor’s exterior framing, which explains the loud banging sound. As such, regular aircon servicing helps to detect such problems. Click here to find out the top 5 benefits of servicing your aircon unit regularly.

Screeching Sounds

The fan motor is a vital part that enables the aircon unit to do its job as it blows air in and out of the house. Malfunctioning fan motors in the outdoor condenser unit can cause an aircon unit to produce incessant screeching sounds.

Screeching sounds can also be caused by damaged bearings in your fan motor. Aside from that, you might want to inspect to see if the fan belt needs repair. Read this article for 5 aircon unit parts that require regular maintenance.

Humming Noises

The purpose of an aircon unit relay is to send electric power to the aircon unit compressor and compressor clutch when it receives a signal from your thermostat. When the aircon unit relay switch is defective due to electrical or mechanical damage, a humming sound can be heard.

Buzzing Sounds

A buzzing noise from your outdoor condenser unit could be a signal for loose parts, damaged blowers, or even unbalanced fan blades. Do also check if there are any aircon issues with the condenser coils as they may become clogged with dirt or dust over time.

In the worst-case scenario, it might be due to a refrigerant leak, resulting in your aircon unit freezing up. If your aircon unit is running outside but not cooling inside, this could be why.

Clicking Sounds

It is normal for your aircon unit to make a clicking sound at the beginning or end of your cooling cycles. It usually means that the thermostat is communicating with your aircon unit.

However, a continuous clicking sound from your aircon unit may imply that there is an aircon issue with your aircon unit. This type of clicking sound may be an indicator of an electrical problem or a problem with the compressor.

In that case, please turn the aircon unit off and call the professional aircon servicing company to examine your aircon unit immediately. Here’s a guide to choosing a suitable professional aircon servicing company that caters to your needs.

Hissing Noises

One reason you may hear a hissing or whistling sound coming from your aircon unit is that there is a refrigerant leak, resulting in an escape of gas. This poses a serious aircon issue as the loss of refrigerant can lead to damage to the compressor, which can jeopardize your entire aircon unit. Read this article for 8 incredible tips on how you can check if there is an aircon unit gas leak.

It can also be caused by an internal valve leak or a malfunctioning compressor.

If you’re only hearing periodic hissing noises, it is most probably caused by the expansion of the internal valve, which is not a problem. Otherwise, you might want to contact the professional aircon servicing company immediately to find out what’s wrong and to fix the aircon issue as soon as possible.


A gurgling or bubbling sound can be caused by excess moisture due to a blockage, crack, or hole in your drainpipe.

The aircon unit drain pipe, otherwise known as the condensate drain, is used to drain the moisture your aircon unit collects from the air outside of your home. However, if something is clogging the drainpipe, it will create a gurgling noise since the water will not be able to exit your home easily. To learn about other causes of the gurgling noise, click here to find out more.

If you are a handy individual with the tools and equipment required, you might want to consider turning off your aircon unit and inspecting the drain line on your own. Otherwise, please call a professional aircon servicing company to ensure a proper job is done. If you’re choosing between calling a professional aircon servicing company or servicing your own aircon unit, you might want to read this article.


It’s always a good time to talk about the common issues that aircon units have. This way, you’ll be able to spot if there are problems with your unit or not and prepare for its replacement accordingly. If you require our aircon servicing services, Whatsapp us at +65 9222 4141 for a fast and transparent quote.

338 Aircon Servicing Singapore provides an extensive range of Aircon Services including Aircon Servicing, Aircon Repairs, Aircon Installation of best aircon brands, Chemical Overhaul, Gas Top-up, Aircon Leaking Water, and Aircon Not Cold Fix and more. We have a team of professional technicians who are equipped with vast knowledge and experience in the Aircon industry.

We have over 15 years of experience in dealing with aircon works and have completed thousands of aircon works for both residential (Landed, Condo, and HDB) and commercial. We are a highly recommended Aircon Company in Singapore, with many delighted customers and reviews over the years on Google and Facebook.

WhatsApp us at +65 9222 4141 for a transparent quotation and honest pricing for all your aircon needs or Call us at +65 9222 4141 . We offer a fast and efficient service to serve any of your aircon needs!

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