i had my hood open while my car was warming up, and i noticed a part in the engine that would turn off and on by itself... i took a little video, check it out in this link http://tinypic.com/r/1z5qaeb/6 sorry, you gotta tilt your head to the left when you watch it because i took it on my phone....
wondering if someone could enlighten me on whats happening here

 

that's the air conditioning pump. it has a "clutch" mechanism that engages the pump to circulate the a/c system. that's normal.

 

It also runs with the defroster on.