I searched the service manual PDF's, there's nothing in the maintenance section or the A/C-related sections about a cabin filter or replacing it. The only related reference I see is this, on Pg 12 of section VTL:
Item 3 there is a "filter cover", and that's the blower unit under the passenger side, probably where you were looking. But still, no mention of a cabin air filter or ever needing to replace one.