300M: What / where is "air pump filter" ?

[MoPar Man]

After 4 years and 60-odd-thousand km it seems that my "air pump
filter" is one of the items to be inspected at my next service.

Where exactly is that filter?

 

[Red Cloud]

After 4 years and 60-odd-thousand km it seems that my "air pump
filter" is one of the items to be inspected at my next service.

Where exactly is that filter?

It's in big plastic rectangular box usually connects with big plastic tube.