Diagnosis
This is usually the Auto Protect mode activating. The unit’s sensor detects a rapid increase in airborne particles.
How to Fix It
Check for activities that generate sudden particles. Cooking smoke, dusting, or someone walking by with dusty clothes can trigger it. It will ramp down after several minutes of cleaner air. You can switch from Auto to Manual mode to maintain a constant speed.
If That Didn't Work
The internal laser particle sensor may be dirty. Power off and unplug the unit. Use a can of compressed air to gently blow into the small sensor vent slit on the side of the unit to dislodge dust.
Heads Up
In a very dusty environment, Auto Protect may activate frequently. This is normal operation, not a defect.