The "filter" is not accessible on the 3rd gen Maximas.  They consist of 2
small screens that are inside the valve body.  There is another screen that
is inside the main case.  Don't worry about servicing these as they rarely
cause problems.  If one should happen to be clogged, you'll have big trouble
with major internal parts being worn and torn.

Chris
90 & 94 GXE's