I always thought there was something about the flight deck getting 100% fresh air or at least more than the cabin, supplied from the left pack rather than the mix manifold?
Although I've noticed on the ground with the packs off, there is still some air coming through the gasper vents in the flight deck, which I can only assume is from the recirc fans. Where exactly are these fans located and where does the air come from/to? I've noticed they are quite noisey in the cockpit.