a stupid sound comming from front driver side

[miller347]

ok its been doing this off and on for a month or so. but as im driving (it dnt matter what seed,slowing down or driving normally) and i hear like a air then one good click. i know it sounds stupid but it almost sounds like the automatic 4x4 kicking in . ive look under there and nuttin is out of place as i see ? any ideas ?

p.s . it dnt do it sitting still so its kinda hard to trace down