when a/c turned "ON" i fill shacking into my sit? and x5 body! why?

[bosanci28]

i wanted to know if this is normal or something will go bad very soon!

when the car runs without the a/c on engine and the car runs fine and the rpm at 600. (no shacking!)

now when a/c is turned "on" the rpm goes higher and i fill the chair under me shacking ,and like the hole x5 shacking little (this is when i am stopped with my foot on the brake) ... is like the a/c works really hard or??,(the a/c pushes cold air out,so it works fine)


is this normal ? anyone had this going on with your x5?

any ideas why,will appreciate!

thanks