Pollen Filter

Bear With Me,a New Member. I Have A Fiat Maxi With A Motor Home Conversion. Owned Since New And Now With 85,000 Kilometers Recorded. Year 2000 And 2.8 Tdi Motor. It Has Been Very Reliable Having Travelled From Southern Spain To The North Cape And Many Countries In Between. Serviced Regularly And Very Few Replacements Fitted. Problems Being Limited To An Oil Leak When New, Camshaft Oil Seal Damaged In Assembly. A Water Leak When Metal Pipe Behind Cylinder Head Corroded, My Fault Should Have Replaced Coolant Earlier.
I Wish To Replace Or Clean The Pollen Filter On The Cab Fresh Air System As There Is Almost No Air Getting Through To The Cab. Can Anyone Tell Me How To Do This,what Needs To Come Off?. Exactly Where Is This Filter ?. I Have A Reasonable Set Of Tools And Some Experience Of Using Them, On Racing Motor Cycles, Not Vans Or Cars. My Third Fiat, Citroen, Peugot Van, All Quite Reliable And I Would Have No Problem With Buying Another, Not Perfect But Then What Is?. Thankyou To Anyone Who May Have Advice For Me.

It is located under/behind the black plastic moulding at the base of the windscreen ( on the outside where the wipers are ) which has to be removed to get access - on which ever the passenger side is - R/H, L/H drive etc