help me find disconected wire

Hey all. I got a question?. . .
Mite sound silly. but....
I looked everywhere and could not find this thing.
It looks like hose type wire it conects in the compresor looking unit
on left side of the car under the very bottom left corner. It's also got metal type holder on in.
It's disconected from somewhere. Where does it go? It's about 10 inch long. Looks like air could travel inside it. If i car find more info on it post soon.

thanks all.