Is a rattling indoor unit always serious?

No. Light rattling is often panel, filter, or louvre vibration. It becomes more concerning when the sound is heavy, grinding, or paired with weak airflow or poor cooling.

Can a dirty unit cause indoor noise?

Yes. Dust buildup on the blower or airflow path can create imbalance and vibration sounds. It can also reduce airflow and make other sounds more noticeable.

Why do I hear water sounds inside the unit?

Some water movement sounds can be normal. If the sound increases, or appears with leaks, weak cooling, or ice, the drainage or cooling condition should be checked.

What should I send for noise diagnosis?

A short video with audio that captures the sound and shows whether it changes with fan speed is the fastest way to help triage.

Aircon Indoor Unit Noise

Not all indoor unit noises mean a part is failing. Some are minor vibration sounds. Others point to fan or water-flow issues. The sound type and timing matter more than volume alone.

Common Causes

A symptom is just a starting point. The same problem could be a quick fix or a major failure. The paths below show the most common causes, but only a proper check can prove what is really wrong.

Panel, Filter, Or Louvre Vibration

Usually Minor

Indoor plastic panels, filters, and louvre pieces can shift slightly and vibrate while the fan runs. This often creates a light rattling or buzzing sound without affecting cooling.

Noise changes when the louvre angle changes.
Cooling performance still feels normal.
Noise is light, not heavy or grinding.

The Fix: We check panel fit, filter placement, and louvre movement first. Minor vibration issues can often be corrected without part replacement.

Watch out: Do not jump straight to fan motor replacement when the sound is a light rattle. Fit and vibration checks come first.

Indoor Fan Wheel Or Fan Motor Wear

Needs Diagnosis

A worn fan motor, loose blower wheel, or fan imbalance can create repeating mechanical noise. The sound often follows fan speed and may come with weak airflow or uneven airflow.

Noise rises or changes when fan speed changes.
A rubbing, humming, or repeating rotational sound is heard.
Airflow feels weaker or uneven compared to before.

The Fix: We check the fan path, blower condition, and motor behavior before recommending any repair. The sound source must be identified directly.

Watch out: A dirty blower can mimic motor noise. Airflow and buildup checks should happen before naming the motor as the cause.

Drain, Ice, Or Flow-Related Noise Pattern

Needs Diagnosis

Gurgling, dripping, or changing flow sounds can come from drainage issues, freeze-thaw behavior, or abnormal refrigerant-side conditions. The timing and other symptoms are the key clues.

Noise appears with water drip, weak cooling, or ice on the pipe.
Sound is stronger during shutdown or shortly after shutdown.
Indoor noise started together with leak or cooling issues.

The Fix: We check drainage and cooling behavior together. If freeze-up is involved, we identify whether the cause is airflow restriction or refrigerant-related.

Watch out: A water sound can be normal in small amounts. If it comes with leaks, weak cooling, or ice, it is no longer a sound-only issue.

Not Always A Fault - Some Startup And Shutdown Sounds Are Normal

Light clicks from plastic expansion or a small water-flow sound can happen during startup and shutdown. These sounds are usually brief and do not affect cooling performance.

How to tell

The sound is brief and happens at the same point of startup or shutdown.
Cooling and airflow remain normal.
There is no burning smell, scraping sound, or water leak.

If the sound becomes louder, continuous, or starts affecting cooling, get it checked.

What To Note Before You Contact Us

The sound pattern is the most useful clue. Note these:

Sound type: rattle, hum, rubbing, gurgle, drip, or clicking.
When it happens: startup, during running, fan speed changes, or shutdown.
Whether airflow or cooling changed at the same time.
Whether water drip, smell, or flashing light appeared with the noise.

A short video with audio is very helpful because sound words mean different things to different people.

Stop Using The Unit If You Notice These

These are not normal noise patterns.

Burning or electrical smell
Loud scraping, grinding, or metal contact noise
Breaker tripping when the unit starts
Water leaking onto electrical points or exposed wiring