Saturn 2004 Ion Owner's Manual page 138

4. Open the passenger compartment air filter door by
reaching through the opening in the back of the
glove box and raising the tab until the door can be
opened downward.
3-26
5. Remove the filter by sliding it out of the housing.
When installing a new air filter make sure the AIR FLOW
arrow is pointing downward. Reverse Steps 1 through 5
making sure the glove box door snaps back into place.