On Turbo or the highest setting, yes, it will be noticeably louder—that's the fan moving the maximum amount of air. But it should be a consistent "whoosh" of air noise, not a rattle, buzz, or whine.
- Make sure the unit is on a hard, level surface. Carpet or an uneven floor can amplify vibrations.
- Check that the front grille is securely snapped into place. A loose panel can vibrate.
- Open the grille and ensure the filter is seated properly and isn't warped or damaged. A misaligned filter can cause turbulent airflow noise.
IF THAT DIDN'T WORK: If the noise is a metallic rattle or grinding, see the answer for grinding noises. If it's a high-pitched whine or hum, the fan motor may be defective.
HEADS UP: For nighttime use, use the lower speed settings which are much quieter. The highest setting is for rapid air cleaning when you're out of the room or don't mind the noise.