vaccum leak check?

[Derek]

after i turn my car off i hear a hissing noise only for 2 seconds, sounds like a valve that let's air in or out is shutting or opening i dont know and i looked at it it almost looked like it was coming from the A/C but i didn't have it on, also after cleaning my IAC valve the car started to make the whistle noise (should be the other way around i should have cleaned it because it made the noise) . Anyways i was wondering how can i check for vaccum leaks or do i have to have a mechanic do it?

 

[Diff Whack Daddy]

Most likely the vent controls bleeding off pressure. Both my Explorers do it as well.