I'm trying to figure out the relationship between the Bioweapon mode and the HEPA filter. It seems like in order to utilize Bioweapon mode, the fans need to be on full tilt - which makes sense, it needs to create positive pressure inside the cabin. Gets a bit annoying though when you want to use it. But what about the HEPA filter? Is that always working, regardless of fan speed or mode? Does it work in recirc, or fresh air mode, or both?