2000 Ford Taurus hoses

I disconnected a hose and i dont know from where or what its called its clamped to the car under hood its a very thin hard plastic hose any idea where it connects to but the side i know connects to a black box with four hoses coming out of it on the box it has the little ford logo in the middle upper left hand side A/C upper right corner B/B botton left corner S and bottom right corner AI


Also there a loud hissing noise when the engine is running sounds like it is coming from the upper or lower intake area? Please help me!!!!!