It does the same thing a filter in your home heating/AC unit does. Filters out junk in the air. Alot of vehicles dont even have them. some have the slot but wont put the filter in.
NAXJA Member #2619
1995 Jeep Sport Cherokee 4x4 with an Auto and 4.0L
B&M Transmission Cooler and Autometer Tranny Temp Gauge, Ruff Stuff Diff Cover on D30.
Taraflex 1.5" BB (rear shackle only), HD Quadratec leaf springs, RE 3.5" front springs, OME Long shocks, JKS Adjustable Track Bar from K.O.R.
Daystar Control Arm Bushings, Bushwhacker Flairs, Rhino lining along bottom trim, AGR PS pump with Cooler & Filter.
Bored TB, APN Manifold, New Downpipe, Magnaflow High Flow Cat, Flowmaster Super 44.
Dual Oil Relocation Kit running two K&N301 size filters, Autometer Digital Cobalt Oil Temp and Oil Pressure Gauge.
I've seen this doen to TJs with a K&N type filter under the cowl grill. It's removeable on TJs. I wonder if there's a way on XJs.
By the way, this would be awesome for dusty locals. I spent years in Southern California in the dusty deserts (and mountains). Dust gets EVERYWHERE!!!! This includes your lungs. It seems like tablespoons of dirt come out onto tissues. A cabin filter was moot on the CJ, but XJs have a fighting chance at keeping the dust out.
One of my favorite "ah-ha" moments was when I realized a paint brush is great for getting the dust out of the cracks and crevises of dashboards. It would be great not to have that chore.
the cabin intake is underneath the passenger side cowl. it's unreachable without cutting the cowl. there is no filter on it. however if you want to cut a hole in the cowl, you can put one on it--you can see it at the top of this pic