Can I wire a microwave blower fan to a plug by itself?
See the wiring diagram on the fan. It needs a starter capacitor between the red and yellow wires; then power (black and white from the plug) can be applied to black and blue for high speed or white and blue for low speed.

There is no ground wire for the fan -- hopefully it is either in a plastic case or otherwise double-insulated so it doesn't need one -- so the green wire from the plug can be left unconnected.