One of my fan motors burned up on my AC unit. The one that burned up is a 1/8 HP with .9 Amps. The new one that I have is 1/4 HP with 1.2 Amps. Can I use the 1/4 HP motor with 1.2 Amps and just change the capacitor to the right size or is this not posible? Will it mess other things up?

It will hurt the efficiency. If the refrigerant charge is ever checked it will throw that off some to. It will run louder, but it will work