In my 96 f150 with a 4.9 there is a vacuum diaphram on the blower box with a white vac line going it it. What does it go to and what does it do? Please let me know. also there is a black relay thingy with a round **** like top next to the A/C condensor that has vac lines coming to it from the intake and then leading to the charcol purge container what it that and what does it do. Thankyou