There is an article here on how to change an air filter ; http://www.carbasics.co.uk/how_to_change_air_filter.htm
how to change a 2009 VW Jetta Air Filter and location
It is pretty easy to replace the air filter in a 2005 Suzuki Aerio. Remove and open the air intake manifold, remove the old air filter, put in the new filter and reattach the air intake manifold.
how to replace cabin air filter in 1999 Mercedes e320? how to replace cabin air filter in Mercedes e320?
How to Replace a Cabin Air Filter on a 2006 GMC
Unless it was added. The 1994 Jetta was not equiped with a cabin filter.
On the air box for the air filter
Purchase a Purotor filter. It comes with complete instructions.
Remove the passenger side kick plate in your 2004 VW Jetta. Remove the cabin air filter container cover. Lift the air filter out and drop in the new cabin air filter.
Changing an air filter on a 2005 Honda Accord requires opening the air box in the engine bay. Remove the clips that hold it shut and open the box. Replace the filter.