Change the filter when the filter life indicator light switches to red. Pull the filter out. Insert the new filter in its place. Press the "Reset" button to reset the filter life indicator light.
Plug the unit into a 120-volt electrical outlet and firmly close the purifier's door if the unit will not operate. Turn the control knob to "On" and select a speed to attempt to turn on the purifier.
Check the air inlets for blockages and clear them if you notice decreased air flow.
Wash the air inlet grill in warm soapy water after removing it from the air purifier if you notice a buildup of dust and dirt, or decreased air flow. Allow it to dry thoroughly before replacing it. Clean the outlet grills with a soft brush if you notice dirt or dust buildup.