On the AC Unit Controls, to the right of the round knob is a button dedicated to the "pollen and dust filter". Per the manual, if you select it, it turns recirulation (left side button) on and will run in this mode for up to 3 minutes. Ok, I'm having a real blone moment here, is there really a second air path that bypasses this filter? I always assumed that the cabin filter was used when recirculate was on. So whats the real story here?
If it's anything like the normal Prius, then it totally closes off outside air, turns up the fans speed and filters out the internal air. That might sound like just using recirculate function but that doesn't totally block off the outside all flow. It restricts it, but not totally blocked off unlike when using the filter option. The reason being is you'd die off without air coming in when using recirc as the car is pretty air tight. This is why the filer function has a built in timer.
Search is our friend http://priuschat.com/forums/gen-iii-2010-prius-main-forum/97739-cabin-filter-button.html I came from a generation 2, so missed that nifty button.
