Low-Rise Condo Bedroom Rattles: Trunking Cover Came Loose

A bedroom rattles and opening up the indoor unit is proposed. Whether the unit produces that sound or something beside it does.

By Team Snowflake | Updated 24 Aug 2026

Teaching case based on recurring Snowflake service patterns; identifying details are combined.

How this presents

A rattle in a bedroom whenever the fan runs, stopping the moment it does. The indoor unit itself sounds normal at the casing. The noise seems to come from along the wall rather than from the unit.

Setup: Fujitsu Wall-mounted4-6 yearsCondoTanglin
Misread as: A fault inside the indoor unit, which will mean opening it up to reach.
Check first: Whether the noise stops when the trunking is held by hand

What else produces this

A sound that appears and disappears alongside the fan, without seeming to originate at the casing, suggests something the unit drives rather than something inside it. Trunking runs from the unit along the wall and carries every vibration the unit produces. A cover that has come loose from its base taps against the wall for as long as the fan turns. Holding it steady while everything is running answers this with no tools at all.

A rattle that arrives and stops with the fan confirms the unit drives it, without locating it inside.
Sound coming from along the wall rather than the casing points away from the machine itself.
A trunking cover that stops rattling when held by hand identifies the source conclusively.
A released cover clip explains the movement.

Why it happens

A run of trunking is two parts: a base screwed to the wall and a cover clipped onto it. The cover is held by friction and small clips, and vibration from the unit reaches it through the pipework inside. Once a clip releases, that section can shift a fraction, and it taps against the wall or the base with every cycle of vibration. Nothing on the aircon itself has changed at all.

What resolution involves

The cover is reseated and clipped properly, ending the noise for the cost of a minute. The habit worth taking away is broader than trunking: when something rattles, put a hand on each thing the unit touches in turn. Whatever goes quiet under a hand is the source, and that test beats any amount of listening.

How to tell it worked

The fan run at every speed afterwards rather than one. A cover reseated at one point can still be loose further along, and it usually shows at the higher speeds first.

Before you approve a quote

Hold each thing in turn until something goes quiet

Everything the unit touches vibrates with it. Some of those things are louder than the machine.
Put a hand on each candidate while it runs. Whatever goes silent under a hand is the source.
A rattle from along the wall rather than the casing points at trunking, pipework or a cover.

Questions this case answers

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

The indoor fan was sound. The rattle came from the trunking cover, which had released from its clip and tapped against the wall while the fan ran.

Why is the noise only there at one fan speed?

Because the released cover only moves under the vibration that reaches it at that speed. Running the fan at every speed afterwards is the check, since a loose cover usually shows at the higher speeds first.

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

No, it points away from the unit. A sound from along the wall suggests something the unit drives, such as a trunking cover that has come loose from its base.

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

A video showing the indoor unit and the trunking along the wall while the rattle is happening. Seeing where the sound comes from helps confirm the cover before anything is opened.

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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