today i had the ac blasting on max at a red light, when i turned it off the car kinda of "leaped" forward (good thing i had my foot on the brakes) is this just because it takes that much power to run it? also the past couple of days the cold air from the ac wasnt working, im guessing somethings wrong with the compressor since the thing that sticks out of it wasnt spinning, any ideas?
And about how hard its it to change the bearings in the alternator since the are going bad?

thanks!