The car likes to UN-set your recirculate setting on a whim. The only way to keep it on recirc seems to
be, set the system for face-only. Since I don't use it for the most part in nice weather, I also set "driver
only" and the close all the dash vents [slide the knobs toward the outermost limits, I think it is].
Obviously if you do this and keep the windows closed you'll fog up inside prety quickly..
_H*