Tip #1

Look for a window air conditioning unit with a sleep mode, quiet mode, or nighttime mode.  These modes of operation have been optimized to provide the most quiet operation possible out of the air conditioner.

Tip #2

Look for manufacturer published sound data.  Manufacturer's that regularly publish sound data of their window air conditioners are Frigidaire, Sharp, LG, Soleus Air, and Sunpentown.  Look for noise ratings at or below 50db for the low airflow mode of operation.  This will be among the quietest of the published air conditioners.  The modes listed in Tip #1 should be below 50db, however this cannot be guaranteed unless the manufacturer publishes that data.

Tip #3

Size matters on window air conditioners.  Larger ac units are typically louder than small units.  For bedrooms consider keeping the door closed to minimize the square footage to be cooled.  This will allow a smaller ac unit selection and should be a more quiet unit at the smaller cooling capacity.

Tip #4

Along the lines of Tip #3, see if the unit can be placed outside of the room in which quiet operation is desired.  If doors can be shut to trap the cool air in the adjoining room and the desired quiet room.  It may be difficult to reach the desired level of coolness if airflow is poor.

Tip #5

Follow the manufacturer installation instructions as well as possible.  Poor installation can lead to excess noise that would not otherwise be present.  Manufacturer's generally include very detailed instructions on installation of the units as this is a key point of the product.