LG LW8017ERSM Owner's Manual page 21

High pitched Chatter
Today's high efficiency compressors
may have a high pitched chatter
during the cooling cycle.
Pinging or Swishing
Droplets of water hitting
condenser during normal
operation may cause
"pinging or swishing" sounds.
(See the section on Slinger
Fan, page 19)
Vibration
Unit may vibrate and
make noise because of poor
wall or window construction
or incorrect installation.
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Sound of Rushing Air
At the front of the unit, you
may hear the sound of rushing
air being moved by the fan.
Gurgle/Hiss
"Gurgling or hissing" noise may be
heard due to refrigerant passing
through evaporator during normal
operation.