happy new year to all!

p- i don't think my ex 86 300E had a cabin filter. i could be wrong!
a- see details below.
j- unsure if applicable on 190.

the cabin filter install on my 95 C-280 went as follows:

the filter install is pretty straightforward and should take about about 15 minutes of your time with only a small degree of contortion.

the filter is located under the dash on the passenger side. remove the cover panel from the dash botton (under the glovebox) with the 3 or 4 phillips screws attaching it in place. your will see a black housing with 2 white sliding retainers that opens to access the filter. this is located toward the front of this area near the transmission tunnel. slide the 2 clips to the full open position, and the cover plate should then simply pull away. if your filter is as bad as mine was, you may want to place a plastic bag under the cover and filter before removing it to catch all of the CRAP that will end up on your carpet when your remove the filter from this housing! the filter is pretty big, and will require a bit of manipulation or rotation to free it from its home. if your filter is any WORSE than mine, you may want to place a WILD RODENT TRAP there in case your awaken the squirrel family living there! reinstall the new filter by reversing these steps, and:

bask in the LUXURIOUS flow of freshly scrubbed air blowing your hair like a rock star! (or cooling your bald head as the case may be)

all in all; it's a pretty easy way to clean out some of those old german ions, and may actually help to improve the airflow and performance of your ACC system.

the 202 that i bought was very clean and was garaged most of its life. it showed very little if any signs of debris in any of the nooks and crannies under the hood or in other areas that would normally be suspect. having said that, the filter which i am sure was the origional was FILTHY and loaded with all manner of crap. it HAD to have a negative impact on the ACC system and airflow.

good luck! - benton in atlanta