Oreck AIR RESPONSE TURBO Owner's Manual page 6

Particle Count
Blue Light Purple Light Red Light
Low Medium High
Auto
Speed Control: Auto Mode: Air Quality Indicator Light
Lets you know auto mode is working by changing
Manual Fan Speed: L=Low M=Medium H=High
colors depending on the amount of particles in the air.
Auto Mode: The dust sensor will automatically adjust the fan speed
based on particles detected in the air. Night Mode: Dims the lights and
turns fan speed to low for easy sleeping.
The Air Quality Indicator Light will remain blue in manual mode.
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