how do you replace the alternator

There is that big SEARCH THIS SITE FOR ANSWERS button on top of the screen my friend.

Give that a try.

P.S. It's Infiniti, not infinity.

Welcome to NICO.

Make sure you loosen the nut on the idler pulley first then loosen alternator belt tension thru the idler pulley adjuster (top, long nut). Access to the nut is tight but once loose, the others will be easy to do. Here's a YouTube video of alternator belt replacement on a Maxima (similar to I3), courtesy of "boredmder." This will give you an idea on how to loosen the alternator belt so then you can take out the alternator.

http://www.youtube.com/watch?v=bJzpTHIky18

when I changed I went through the bottom of the car... when take the belt off i did removed the AC compressor and left it hanging on hoses then swapped alternator.. I think it has 3 screws . recommend flexible ratchet head that makes reaching things easier.