Is there such a thing as a window air conditioner that does not make an annoying low-frequency throbbing while the compressor is running?

I do understand how this works, we have a high-power 60 Hz motor running a high-pressure pump, and you can hear the 60 Hz line frequency as everything inside the pump vibrates in sync with it.

I understand electronics and I know that we could have compressor motors that don't run on 60 Hz AC.

  • We could have a DC-motor compressor with an electronic AC to DC voltage converter.

  • We could have a three or more phase compressor motor driven by an equally tiny variable speed drive (also known as variable frequency drive), with a carrier frequency of 16kHz or more so it's not audible.

By eliminating the 60 Hz driving frequency we could make the compressor, and the "window shaker" in general, essentially silent except for the noise from the blower, and refrigerant gurgling through the tubing.

But the question is, does such a thing exist? So far my Google searches are not turning up anything.

  • You could use a split-unit where the compressor is located far from your room and all you hear is the fan.
    – Johnny
    May 31, 2017 at 0:02
  • I do not have permission to modify the building, so it has to be a window unit. May 31, 2017 at 0:13

1 Answer 1


The source of the noise is the motor, compressor and fans spinning. A DC air conditioner would make the same sounds.

The AC power frequency enters the picture because the cheapest-to-build motors are induction motors, which spin at slightly less than line frequency. As such the noise frequencies tend to be in the 48-49 Hz or 58-59 Hz range.

Often there is also a "rattle" from something coming loose. A healthy unit should not rattle, but this is rather hard to fix.

The reason air conditioners are flippin' loud is they are cheap. Of course there is consumer demand for quieter air conditioners, and the units are out there for the discerning shopper. They are more money and most people don't want to pay it. Or when they are shopping it doesn't occur to them to make it a priority.

  • 1
    My understanding is that most of the vibration is not even from the motors, but from the compressor itself, which has a big piston swinging back and forth. More expensive and larger units have different designs, e.g. scrolls, which are almost silent. Smaller inverter units have compressors that max out at ~4k RPM, and you can definitely hear them. May 31, 2017 at 7:26

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