My portable air conditioner's compressor can get quite noisy, it's like a vibrating pulsing grinding noise. Is it possible to reduce this noise?


There should not be any "grinding" but scroll compressors used in AC systems do have a large amount of vibtation they are normally mounted on 3 or 4 rubber vibration isolators for this reason. If you want to dampen a small window unit for example I have used 1/4" rubber sheet under the system to further isolate the noise, I would be cautious about the type of insulation as last year a friend had tried to put fiberglass around his new unit and although it worked he used two muck and the unit fell out and dammaged both the outlet it was plugged into and the condensing coil on the unit that was not repairable.

  • Yes the compressor in my unit does have rubber isolation feet. When I am able I want to try and see exactly what's making the vibrating rattling noise with the housing covers taken off. Can the noise be inside the compressor itself? – Kol12 May 5 '19 at 12:06
  • The compressor are noisy, I don't think they sound like grinding but they do buzz, other than that there are 2 fans usually driven off the same motor, if not set up correctly one of the fans (squirrel cages most of the time) may be rubbing. – Ed Beal May 5 '19 at 15:24
  • The biggest contributor to noise can be resonance in the wall and window. Putting a reinforcing member under the air conditioner and putting vibration-damping foam (e.g. a foam-rubber kneeling pad) on the window might help. – DrMoishe Pippik May 5 '19 at 19:55
  • This is what I recomended, not the same wording, but not resonance, just simple vibration, having a degree in electronics and being a professional electrician I have only found resonant cavities 2 times over close to 40 years and both were light commercial facilities, the sonic vibrations was actually damaging the concrete in the first and creating huge standing wave interference in the second (a hospital) in both cases vibration from pumps was the cause. Simple addition of additional isolation in both cases fixed the problem. – Ed Beal May 5 '19 at 22:47

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