LG AHNW146A0 Owner's Manual page 18

Owner's instruction
Silent Mode Operation
Silent mode operation is that the outdoor unit works at reduced capacity so that the noise produced
by the outdoor unit drops.
This implies that the indoor heating and cooling capacity will also drop. Beware of this
when a certain level of heating or cooling is required indoors.
Silent mode operation may not work while the product is proceeding higher priority
operation such as defrost operation, anti-freezing operation, and etc.
((When this mode is not operated by the priority order, ONLY display
18 Air-to-Water Heat Pump Owner's Manual
1 Press Silent Mode Button.
This button ON or OFF silent mode.
<Silent Mode OFF>
<Silent Mode ON>
.)