A clogged filter is the most common cause. Check and clean the pre-filter; replace the HEPA filter if needed.
- Unplug the unit.
- Open the grill cover and remove both filters.
- Rinse the mesh pre-filter with water and let it dry fully.
- Inspect the pleated True HEPA filter. If it's dark gray and packed with dust, it needs replacement.
- Reinstall the clean/dry pre-filter and the (new or existing) HEPA filter correctly. Ensure the grill cover is sealed.
If that didn't work, verify your speed setting. With the unit on, slide the SPEED selector bar fully to the Turbo position. Listen for a distinct increase in fan noise. If the sound doesn't change, the speed selector switch may be faulty.
Heads up: For optimal performance in its recommended 465 sq. ft. space, ensure at least 6 inches of clearance around the air intakes and outlet.