Aircon making noise: normal sound or fault?
Not every sound means something is wrong. Valves and the flap move as the unit runs, and some of them make sounds. Other sounds, such as grinding, scraping or a loud rattle that does not stop, need a technician to find the cause.
What counts as normal differs by brand and model, so the manual for your own unit is the first reference. Daikin's troubleshooting page explains several sounds for Daikin units, set out in the next section. It is Daikin's global page, so follow your own model's manual too. For another brand, ask the maker.
Noise from the indoor unit
Daikin explains four indoor unit sounds for its own units. Daikin says a clicking sound may come when the refrigerant control valve or an electric component operates, and a buzzing sound when the flap moves. A rattling or creaking sound may come when the flap position is adjusted at start-up or stop. A bubbling sound may come when air enters the drain hose, which tends to happen in a well-sealed home, and Daikin says a drain hose check valve can be used to control thumping and knocking sounds.
So aircon rattling for a moment as the unit starts or stops can match the flap adjustment described above. A rattle that keeps going during cooling, or grows louder, does not fit that description: treat it as abnormal and follow the switch-off steps below. For another brand, check its manual or ask the maker.
There is no single explanation for an aircon hissing sound that holds for every model. If a hiss comes with poor cooling, have a technician check it, and read about the signs of an aircon gas leak. For any indoor noise your manual does not explain, an aircon repair company can check the cause.
Noise from the outdoor unit
For the outdoor unit, look at how it is mounted as well as how it sounds. HDB's home care guide asks owners to inspect their aircon regularly: brackets must be fixed to concrete or brick walls, not timber frames, and stainless steel brackets should be free of corrosion and rust. HDB says to check with your aircon serviceman whether a corroded or rusty unit needs replacing.
HDB also asks owners to have the condensing unit serviced regularly by a licensed service provider, and to ask whether its brackets need replacing because of rust and corrosion. When you book condenser cleaning, ask about the brackets too.
Under HDB's installation rules, owners must maintain the aircon regularly to avoid nuisance to neighbours; otherwise HDB may ask them to stop using or remove the condensing unit. If a neighbour has complained, see our guide to a noisy aircon condenser.
Noises that mean switch off now
Daikin says that if the indoor unit makes an abnormal noise during operation, you should stop operation, unplug the power cord or turn off the circuit breaker, and contact the place of purchase. Daikin gives the same steps for a burnt odour. These are Daikin's instructions for its units; for another brand, follow your manual.
- Stop the aircon. Switch it off with the remote.
- Cut the power. With dry hands and nothing wet nearby, switch off its breaker or unplug it.
- Note the noise. Write down when it happens (at start-up, during cooling or at stop) and whether it comes from the indoor or outdoor unit.
- Get it checked. Contact the place of purchase or a servicing company and describe the noise.
If the noise comes with a smell, read our guide to an aircon burning smell.
What a check or repair visit costs
FROM THE HOMEZYPRO DIRECTORY
Published aircon repair and inspection rates
For the most common unit (per job), the lowest published rates from 11 companies run from S$40 to S$100. Each figure is one company's own advertised rate with its conditions, not a market average or a quote.
See 21 published repair or inspection rates and sources
| Company | Service as listed | Rate | Source |
|---|---|---|---|
| Skyzone Aircon Pte Ltd | Aircon diagnosis fee (residential) | S$27.25 per visit | skyzone.com.sg |
| Snowflake Services LLP | Diagnostic visit (waived if you proceed) | S$30 per visit | snowflakeaircon.sg |
| City Cooling Pte Ltd | Checking | S$35 per unit | citycoolingengr.com.sg |
| A-Max Aircon | Troubleshooting | S$40 per job | amaxaircon.com |
| Blossom Engineering & Construction Pte. Ltd. | Troubleshooting | S$40 per job | blossomaircon.com |
| Coolest Aircon Service Pte Ltd | Aircon Repair | S$40 per visit | coolestaircon.com.sg |
| Doctor Cool | Aircon repair or troubleshooting | S$40 per job | doctorcoolsg.com |
| SmartCool Aircon Servicing Singapore | Troubleshooting | S$40 to S$80 per job | smartcool.sg |
| Thetop Aircon Service | Aircon troubleshooting repair | From S$40 per job | thetop.com.sg |
| Goodcool | Aircon Troubleshooting | S$43.60 per job | bestairconservicing.com |
| Aircon Boon | Ttroubleshooting [sic] | S$50 per job | airconsg88.com |
| Sky Blue Aircon Engineering Pte. Ltd. | Troubleshooting & diagnostics visit (from; waived upon repair) | From S$50 per visit | skyblueaircon.com |
| Jiaxing Holdings Pte. Ltd. | Onsite inspection checking fee (waived if the repair proceeds within 1 month) | S$54.50 per visit | jiaxing-aircon.sg |
| Heng Aircon Pte Ltd | Diagnostic check | S$60 per visit | hengaircon.com |
| Same Day Aircon Servicing Repair | Repair troubleshooting (fix quoted separately) | From S$60 to S$80 per job | urgentairconservicing.sg |
| Vois Pte. Ltd. | Aircon troubleshooting | From S$60 per unit | vois.com.sg |
| Airple | Aircon Troubleshooting | S$60.60 per job | airple.com.sg |
| Lion City Air Conditioner Services | Gas troubleshooting | S$87.20 per job | lioncityaircon.sg |
| Joydom Engineering Pte. Ltd. | On-site troubleshooting visit | S$100 per job | joydom.com.sg |
| Cool-Aire Aircon Servicing | VRF Troubleshooting - On site survey / Transport charges | S$150 per visit | coolaire.com.sg |
| Homeone Aircon | Compressor replacement labour, split (<3hp), parts excluded | S$600 per unit | homeone.com.sg |
In the directory, 21 companies publish a repair or inspection line. Of these, 11 price it per job: their published rates run from S$40 to S$100 per job, with S$43.60 per job in the middle (the middle company's own published rate, as printed). Other lines are priced per visit or per unit, as printed.
These rates are mostly for troubleshooting, checking or a repair visit, not for the repair itself. Parts and repairs are quoted after the check.
Ask whether the checking fee is waived if you go ahead. Some lines say so as printed, such as a diagnostic visit at S$30 per visit (waived if you proceed) and an onsite inspection checking fee at S$54.50 per visit (waived if the repair proceeds within 1 month). For the repair itself, see our guide to aircon repair cost.
NEXT STEP
See aircon companies in the directory with their published prices, the areas they say they cover and their sources.
Compare aircon companiesWhen to stop and call a professional
Call a professional if you notice any of these, and never open the unit's covers yourself:
- a grinding, scraping or loud rattling sound
- any noise together with a burning smell
- an outdoor unit or bracket that looks loose or rusty (HDB asks owners to check with their aircon serviceman whether a corroded or rusty unit needs replacing)
- noise together with water leaking from the indoor unit
Before you book, compare aircon servicing prices or browse aircon companies with their published prices.
Questions
Is a clicking sound from my aircon normal?
Often, yes. Daikin says a clicking sound on its units may come when the refrigerant control valve or an electric component operates. For other brands, check the manual. If the clicking is loud, new and keeps going, or comes with a burning smell, switch the aircon off and have it checked.
Why does my aircon make a gurgling sound?
Air entering the drain hose is one cause. Daikin says this bubbling sound on its units tends to happen in a well-sealed home, and that a drain hose check valve can be used to control thumping and knocking sounds. For other brands, check the manual. If water also leaks, stop using the aircon and have it checked.
Should I spray cleaner into a noisy aircon?
No. Daikin says a commercial cleaning spray inside the aircon may damage resin parts of the heat exchanger and other internal components, and in the worst case cause water leaks. Switch the unit off and ask a technician to check it.
Is it safe to keep using a rattling aircon?
Switch it off if the noise is new or loud. Daikin says that if the indoor unit makes an abnormal noise during operation, you should stop operation, unplug the power cord or turn off the circuit breaker, and contact the place of purchase. Do this only with dry hands and nothing wet nearby, and have it checked.
Who maintains a noisy outdoor unit in an HDB flat?
You do, as the owner. HDB asks owners to have the condensing unit serviced regularly by a licensed service provider, and to ask whether its brackets need replacing because of rust and corrosion. HDB also asks owners to inspect the brackets regularly.
Will servicing stop the noise?
Not always. Servicing is a cleaning job, while finding the source of a noise needs a technician to check the cause. When you book, describe the noise and when it happens, and ask whether a check is part of the visit. Any repair is quoted after the check.
Prices come only from the sourced company rates in the HomezyPro directory, shown with each company and its source.
Practical guidance for planning a home job in Singapore. Company prices come from the HomezyPro directory, each linked to its source; rules and safety points link to the agency or manufacturer that sets them. This is not a site inspection, a quote or professional advice for your home.
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