Low-rise condo bedroom rattles: trunking cover came loose

A Tanglin low-rise condo bedroom rattled most noticeably at night. The unit still cooled, so we checked nearby trunking and casing vibration before treating the sound as a fan or compressor problem.

By Team Snowflake | Updated 28 Jul 2026

Case summary

Fujitsu Wall-mounted9 years oldCondoTanglin, Singapore

Concern: Owner worried the indoor fan was failing because the rattle came from the bedroom wall.
Found: Loose trunking cover vibrating against the wall during fan operation
Key check: Held the trunking cover during operation and the rattle stopped
Result: The bedroom ran quietly after the trunking cover was fixed. The case stayed small because the check followed the vibration instead of the assumed component. That made the repair quick, explainable, and easy to verify before leaving. The owner also knew what to film if the sound ever returns at night, including the trunking beside the unit.

What we were told

The bedroom cooled normally, but a light rattling sound became obvious at night when the room was quiet. The owner thought the sound came from the indoor fan. It was worse at one fan speed and softer when the unit settled.

What we checked

We listened for where the vibration changed instead of assuming the fan was failing. The unit casing, louvre, nearby trunking, and wall cover were checked while the fan ran at the speed that made the complaint obvious. Older low-rise condos can have trunking covers that loosen slightly over time as rooms are cooled nightly.

Cooling and airflow were normal.
The rattle changed when the trunking cover was held.
The indoor fan did not scrape or pulse.
One trunking clip was loose near the wall bend.

What we found

The rattle came from a loose trunking cover vibrating against the wall, not from the indoor fan. The fan speed created enough vibration to make the cover chatter at night, when the room was quiet. Because the sound changed when the cover was held, the noise source was outside the aircon body. That made a fan motor quote unnecessary from the checks we had. The quiet bedroom made the sound feel larger than the actual fault.

What fixed it

We secured the trunking cover, checked the nearby clips, and ran the unit again at the same fan speed. We advised the owner to record future noise with both the unit and nearby trunking in frame, because wall-side vibration can sound like it comes from the unit. No indoor fan replacement was recommended because the rattle disappeared when the external cover was secured. The owner was also told to mention fan speed, because some loose covers only vibrate at one setting.

Outcome

The bedroom ran quietly after the trunking cover was fixed. The case stayed small because the check followed the vibration instead of the assumed component. That made the repair quick, explainable, and easy to verify before leaving. The owner also knew what to film if the sound ever returns at night, including the trunking beside the unit.

What this case teaches us

Bedroom rattles can come from nearby fittings

A rattle near the indoor unit is not always inside the aircon. Trunking covers, casing edges, brackets, and wall fittings can vibrate.
If touching a cover changes the sound, check fitment before approving fan motor work.
Record the sound at the fan speed where it is loudest. Noise diagnosis depends heavily on timing and where the vibration changes.

Questions this case answers

Light rattling near the bedroom aircon at night: is the indoor fan failing?

It was the trunking in this Tanglin flat. The sound changed the moment the cover was held, one clip near the wall bend had loosened, and the fan itself neither scraped nor pulsed. Cooling and airflow were normal throughout. Securing the cover and rechecking the nearby clips ended the complaint.

Why is the noise only there at one fan speed?

Each speed produces a different amount of vibration, and a loose cover only chatters once it gets enough. That is why the rattle came and went as the unit settled. Mentioning the speed where it is loudest is genuinely useful, because some covers stay silent at every other setting.

Does a sound from the wall mean the noise comes from inside the unit?

Not necessarily, and a quiet bedroom makes it very hard to tell by ear. Covers, casing edges, brackets and wall fittings near the unit all vibrate, and the sound arrives from the same direction as the aircon. Touching each one while the fan runs is what separates them.

If the rattle returns at night, what is worth filming?

Keep both the unit and the trunking beside it in frame, and let it record at the speed where the sound is worst. Wall-side vibration sounds like it comes from the equipment, so a clip showing both makes the difference visible. It also stops the next diagnosis restarting from a motor assumption.

Ready to get started?

Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.

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