The Hepa air filtration on the G500 is amazing. Any dust, smoke, whatever in the air in the interior of your car is instantly in this filter once you hit the recycle air fan setting on your console. However, every once in a while you need to clean the filter. The book says replace often, but I blow it out with a compressor most the time.....every year I replace it, but one trip to the desert or any dusty location, and it needs to come out.
1. locate the plenum box, which under the hood, by the firewall, passenger side, large black box
2. remove cap lid for filtration system
3. slide and pull on the framework of the filter, not the filter itself. The filter can tear and you don't want grease on it.
4. remove
5. split filter and framework gasket
6. clean 'em and blow out filter
7. replace same way
.....while I am at it, I also clean out the space under the grill in the hood, which is the fresh air intake for the cabin climate control.
This also includes cleaning out the "gutter" beneath the windshield and under the aft portion of the ajar bonnet.
see photos...