Technically Chile could bombard San Francisco, and interdict all the pacific shipping of the USA, as all of it goes trough San Francisco, but this will not amount to much, especially because a bombardment of San Francisco will send all the USA asking for blood, and as I say in the long run USA will won the war.As someone with little knowledge of Latin American history, looking through this thread it seems like what would happen is that Chile would sink the US Navy, probably keep Panama out of American hands, but not really be able to do a whole lot else, especially since the only way to do something after retaking Panama would be to make an action on the US Mainland which is really really really not gonna be fun.
An interdiction of the shipping is more effective, as damage the USA economy but don´t kill anybody and put heat on Washington to call a white peace, but this is not really effective