It is behind the glove box. My son replaced it, very easy. Just be careful of the glove box latch, plastic. He broke that in his haste and it cost @$25. Found on internet many broke theirs.
That sounds like an air filter for the passenger compartment
In the firewall. Between the engine compartment and the passenger compartment
In the front of the engine compartment , on the passenger side , inside the engine air filter housing
try looking under or behind the glove compartment in the passenger side
The cabin air filter on a 2003 Chevy 2500HD pickup is located on the passenger side under the glove compartment. To replace it, first remove the two screws on the kick plate under the glove compartment. Remove the kick plate. Then, unclip and swing the filter housing cover to the right. Remove the filter by pulling straight down. Insert the new filter, and reassemble in the reverse manner.
It Located behind the glove compartment. Just squeeze the sides of the glove compartment and it will release and hang down. simply open the cabin filter compartment and change filters.
passenger side look under your compartment you will see a cap take that off and replace it
I was looking at the 2003 Ford Explorer Sport Trac Owner Guide and it does not show an air filter for the cabin / passenger compartment , so I would say ( No )
Under the hood, on the far passenger side in rear of engine compartment in plastic air intake plenum.
See Passenger Compartment Air Filter on page 3-26 of your "Owner's Manual", under Section 3: Instrument Panel - Climate Controls.....
The air cabin filter is located in the back of the glove compartment. Open the black plastic door and then the air cabin filter compartment, pull it out and clean or replace. It make all the difference in the world!
The Cabin air filter is in the cowl on the passengers side. To access it raise the hood, look at the cowl on the passenger side. You should see a panel with 5 or 6 black push in retainer clips.