All Lexus AC filter systems work no matter what the rec/frsh air mode is in. The filter is positioned just above the fan's intake side. Be sure to check the filter at least once a year, that's what Lexus recommends. I've seen some so plugged that when the fan is on high it feels like it's blowing on low to medium.
You must remove the glove box door. I've yet to have to yet, but I think you must pull the two pins at the base of the door hinge out. Just above the fan is a long rectangular door about 1.5" in width. Just grab it and pull it out. The filter just slides out. New filter is about $35.00 from dealer. But you can blow them out or tap them on the ground. Most of the clogged filters I have seen are from people who park under a tree daily. Leaves that sit on your windshield will eventually break down into little pieces and get sucked into the filter. Hopes this helps you out.