Max Air Not Blowing/working Help

Hey all,
We have a 97 windstar GL and the Max air blower is not blowing. :banghead: When you turn on the A/C (which is also not blowing very cold) it blows on the normal speed, but when you turn to max speed it does not change speed. Please help wife complaining....

"Max air" recirculates air inside the cabin ... whereas the regular ac settings take in some outside air. Because recirculation is easier for the fan ... it speeds up.

I would look for the reason that the plenum doors (that control air flow) are not shifting when you select "max air". Perhaps a vacuum hose disconnected .. or a vacuum leak of some sort.