AC noise and vibration: what to observe before a repair
Where a noise comes from and when it occurs help distinguish operating sounds from vibration that needs investigation.
Locate it without touching
From a safe position, listen for whether the source is the indoor unit, a grille or the outdoor unit. Note whether it happens at start-up, shutdown or throughout operation. A brief creak is different from continuous rubbing or a metallic impact. Never put objects near fans to test them.
Record the conditions
Make a short recording and note the operating mode and fan speed. Mention whether a normal remote setting changes the noise. Visually check for loose objects resting against the machine, but do not loosen supports or remove covers. Recent building work or servicing is relevant context.
Identify the cause before replacing parts
Inspection may need to distinguish transmitted vibration, fixings and mechanical operation. A recording can help prepare a visit, but cannot confirm a replacement part. If there is violent shaking, a loose mounting or noise accompanied by a burning smell, stop using the equipment and keep clear of the area below the outdoor unit.
Choose the next step
Use the symptom page to understand the likely causes. If the cause is still unclear, book a diagnosis before approving a repair.