A leafy Bandra street seen from a high flat through the diamond mesh of a window grille — Quiet streets make small noises large. Note what the noise does before you ring anyone.

Clicks, rattles and the hum at night

Split AC noises such as light clicks and flap creaks are usually normal, but a new abnormal noise from the indoor unit means stop it, turn off the power and call for service.

From The AC in Your Flat. Updated 4 November 2026.

Listen at three moments: switching on, running steadily and switching off. A sound that comes at only one of those moments tells a technician a lot.

Which split AC sounds are normal?

Daikin's troubleshooting page lists several. A click may be a valve or an electric part working. A buzz may come from the flap moving, and a rattle or creak may come from the flap being adjusted at start or stop. If the airflow rises and falls near the set temperature, Daikin calls this normal too. Some Daikin units also hiss or crackle by design, because of an air-cleaning feature. Check whether your own model has one.

What you hear, and what the maker says
What you hear	When	What Daikin says
Click	Any time	A valve or electric part working
Buzz	Flap moving	Can happen when the flap moves
Creak or rattle	Start or stop	Flap position being adjusted
Abnormal noise from the indoor unit	During running	Stop, turn off the power, contact the seller

When should you switch it off?

Treat grinding, clanking and squealing as faults. A Business Today explainer lists them as signs of mechanical failure and says to have them checked. Daikin's instruction for abnormal indoor noise is direct: stop it, unplug it or turn off the breaker, and contact the place of purchase.

A plain outdoor unit on rubber feet on the terrace of a low-rise society building, with puddles after rain — AI-generated picture. Rubber feet or pads under an outdoor unit are a job for the technician. Society guidance treats noise and vibration as grounds for complaint.

A tree-lined street in the Hindu Colony area of Dadar with parked cars — In a quiet lane, a neighbour may hear your outdoor unit before you do.

An old block of galleried flats on Picket Road in Mumbai, seen from across the street — A rattle at height can mean a loose mount. Report it, and don't reach for it.

Is the rattle coming from outside?

Listen from inside at the window while it runs. The remote stops both units together, so it can't separate them, but a noise clearly coming from outside is a matter for a technician, who can check the bracket and mounts. Do not lean out, climb out or tap the unit to test it. Society guidance also treats noise and vibration as grounds for action, so a complaint from below is worth taking seriously.

What to do

Yours to do

Note when the sound comes and whether it seems to come from indoors or outside.
Check the filter is seated properly, with the power off.
Stop the AC and turn off the power if the noise is new, harsh or getting worse.

Leave to the trained person

Fan balance, mounts, brackets and anything on the outdoor unit.

Also asked

It goes quiet and then starts again. Is that a fault?

Often not. Daikin says the unit drops to a gentle breeze near the set temperature, and airflow can go up and down. It also waits about three minutes if restarted right after stopping.

How quiet should a bedroom unit be?

There is no standard figure we can give you. LG quotes under 31 dBA for one of its models, from its own testing. Compare numbers in the spec sheets of the models you are considering, and treat them as maker figures.

Where this came from

Daikin, troubleshooting: Normal sounds and what to do about abnormal ones
Business Today, 29 May 2026: Mechanical warning signs
NoBrokerHood, AC installation guidelines for societies: Noise rules in societies
LG India, AC capacity guide, May 2026: A maker's quoted noise figure

This story rests on those pages, opened or checked by 4 November 2026, and on no tests of our own. Maker pages speak for their makers, and rules and wiring differ by building, so check your own manual.