RYFM before starting a post
The control cabin, so called cockpit , has a 100% fresh air supply.
The left air conditioning pack supplies the conditioned air for the flight compartment.
The air flows through ducts that go forward along the left side of the airplane.
The flight compartment distribution uses different ducts than the passenger compartmentv distribution.
The flight compartment receives conditioned air from the right pack if the left pack is not operational.
The flight compartment distribution lets the flight crew select a different air temperature than the other areas of the airplane. The air quality is better because it comes from the left pack and is not mixed with recirculated air.
Any questions ?? Don't ask me if U have to wear a breathing gear when U go for a leak 
rgds