Newton condo outdoor unit hums: anti-vibration pads flattened
A Newton condo on a high floor had an outdoor unit that developed a faint but constant hum carrying through the bedroom wall. High-rise ledges here see more sustained wind than lower floors. Flattening anti-vibration pads can transmit that hum long before the compressor is actually wrong.
By Team Snowflake | Reviewed 11 Jul 2026
Case summary
Mitsubishi Electric Wall-mounted15 years oldCondoNewton, Singapore
- Concern
- The resident worried the compressor was developing a serious internal fault after years of otherwise quiet, trouble-free operation.
- Found
- Anti-vibration pads beneath the unit flattened with age, letting normal vibration transmit through the wall
- Key check
- Checked the condition of the anti-vibration pads before assuming a compressor fault
- Result
- The hum disappeared completely once the new pads were properly fitted, even during the quietest hours at night. The resident avoided paying for compressor work that the unit never actually needed in the first place.
What we were told
The resident said the hum had built up gradually over the past year or so, and was most noticeable at night when the rest of the bedroom was completely quiet. It still cooled normally throughout the day. It had run for well over a decade without any similar complaint before this.
What we checked
We treated the gradual, years-long build-up as the first lead rather than opening the compressor straight away. A sudden internal fault tends to appear and worsen quickly. A hum that builds slowly over years more often points at mounting hardware wearing down with age and sustained use instead.
The compressor ran smoothly with no unusual internal noise when tested in isolation from its mount.
The anti-vibration pads beneath the unit had flattened and lost almost all of their original cushioning.
Vibration from ordinary operation was transmitting through the flattened pads directly into the wall.
No refrigerant, electrical, or airflow fault was found anywhere else in the system.
What we found
Over more than a decade of use, combined with sustained wind loading typical of this high floor, the rubber anti-vibration pads beneath the unit gradually flattened and hardened. Once they lost their cushioning, they stopped absorbing the compressor's completely ordinary vibration. That vibration transmitted straight through the flattened pads into the wall behind it. It was most noticeable at night, when everything else in the bedroom was quiet.
What fixed it
We replaced the flattened pads with new anti-vibration pads rated for this unit's weight and mounting position on a high floor. We did not recommend any compressor work, since it tested normally throughout the visit. We advised checking the pads again in a few years, since sustained high-floor wind exposure wears them down faster than sheltered installs do.
Outcome
The hum disappeared completely once the new pads were properly fitted, even during the quietest hours at night. The resident avoided paying for compressor work that the unit never actually needed in the first place.
What this case teaches us
A hum through the wall after years of quiet running often means flattened pads
- A hum that develops gradually after years of quiet operation often points at flattened mounting pads, not the compressor.
- High-floor ledges see more sustained wind loading, which can accelerate how fast mounting pads wear down.
- Ask for the anti-vibration pads to be checked and replaced before approving any compressor work at all.
Related reading
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