It is not really a ball like in the 3rd gens this is like a black plastic cylinder you can see it if you look down behind the headlamp, under the frame rail. There will be one black plastic hose attached to it.

Massey

 

The air doors that direct the flow of air are controlled by vacuum powered actuators. If the available vacuum is too low, the actuators will lose control and allow the air doors to go where ever they want. At WOT there is little engine vacuum, and the AC system depends on a vacuum reservoir to operate properly. Small vacuum leaks will not be noticed during low engine loads (high engine vacuum), but when the engine does not produce vacuum (high engine load), the reservoir will become depleted because of the leak, and the actuators will fail to work.

Additionally, many cars are designed so that at WOT the AC will automatically be disabled in order to provide more power to the drive wheels.

 

i believe that is the evap canister, although i could be mistaken. as for air leaving the dash vents, my dd does it when i get on the highway or its under heavy load from towing. the engine is old and doesnt produce much vacuum, so it turns to the windshield vents

 

The Evap cannister on my car is in the rear behind the bumper. I have diagnosed a vacuum servo issue with my friends car. I mapped out the Vacuum lines and the locations of each unit. The cannister for vacuum storage is the one I discribed above. The evap lines are go from the rear of the car to the purge soloniod on the intake manifold.

Massey