If your room air-conditioner is noisy, Vibration is most likely the cause. Here's how to track down the cause and fix it so that you can stay cool in peace and quiet.

First, tighten the screws holding the front panel onto the unit. Now, check the window around the unit.

Turn the air-conditioner on and press your hand against the sash. If the sound changes in pitch as you press your hand on the sash, put some wooden shims between the window frame and the sash. If the pitch changes when you press your hand on the glass, use some insulating tape between the glass and the frame.

Finally, pull the unit out of the window if the sound seems to be originating from within. Make sure the fan blades aren't bent. If one is, simply bend it back until it matches the others.