I am replacing the compressor fan motor on my YORK unit.

The motor I took out had 4 wires Purple and Brown to the small capacitor, green for ground, and black to a connector.

The replacment motor has 5 wires, the 5th one is white and I dont know where it connects to.

safe to say the motor will not switch on.

Did you buy a new capacitor with the new motor, I am going to assume that you did. So this is how to wire the motor. First if it is a reversible motor write the directions down on how to reverse it.
The two brown wires go the the two separate post on the new capacitor.
The white wire goes to the terminal on the contactor where the yellow wires are connected.
The black goes to the terminal where the black wires are connected.
The wire that is left is a wire left for a two speed motor, so read and make sure that you have a two speed motor. If that is what it is use a wire nut and screw it onto the end of the spare wire.
Now test the motor if it is blowing the right direction you are fine if not read the directions on how t reverse the motor. Be sure and write how they are connected now and then change them to what it calls for.. Now test the motor again. Be careful changing the direction, it can be tricky. Let me know if it works.