Cadillac 2003 Seville Owner's Manual page 143

Passenger Compartment
Passenger compartment air, both outside air and
recirculated air, is routed through a passenger
compartment filter. The filter removes certain
contaminants from the air, including pollen and dust
particles.
routine scheduled maintenance. See Part A:
Scheduled
Mainfenance Sewices on
page 6-4 for replacement
intervals. See your dealer for assistance when changing
the filter.
Your vehicle will not be damaged if you choose not to
replace the filter once the old one is removed.