Whirlpool UltraPure AP33 Owner's Manual page 14

Dust sensor
1. Remove sensor cover on right of unit.
1 Push to release latch
2 Pull in arrow direction
3 Pull forwards
3. Replace sensor cover on unit
Sensor may malfunction without cover.
Filter
1. When cleaning light illuminates, clean the filter.
If filter is not cleaned, light stays illuminated
about one month, depending on conditions.
2. Remove front cover
Grip finger pieces on lower front cover, pull to
release hook and raise to remove front cover.
2. Carefully use a swab to wipe the shiny
surface of the lens.
Lens
Filter cleaning light