What is this? and why is it leaking air?

[folivier]

Not sure what this part is, I'll try and get a picture tomorrow. While I had the engine running after cleaning the radiator, I heard an air leak behind the driver side headlights. Above the solenoid 6-pack there is a small black device with wires, an air line, and what looks like 2 rubber hoses (vacuum lines?) going up where the dash would be. On the bottom there is a nozzle (?) that was blowing air. I did have the dash a/c running (even though it doesn't blow cold) to circulate air since I was going to move it under the cover.
I've never noticed this before, really don't use the dash air since it doesn't work. Is this some type of device to provide a vacuum for the a/c to work? Is air blowing out of the nozzle normal?
Really want to make sure this is not a problem that I should fix before I use it again.
Thanks. Don't you love these little mysteries?