I recently acquired an old air compressor with a 3 wire plug (black,white,green) wires. My only 220v outlet is a four pin receptacle. (red,black,green,white) I understand black and red are hot, white is neutral, and green is ground, but I'm not sure if I can safely adapt my compressor to plug into this outlet.. Any help would be greatly appreciated.. Thank you so much..

The neutral is not needed for the motor, only the black and red live wires, and of course the equipment ground.

If you rather not work on the wiring or receptacle to match the motor, you could use the correct 4 wire plug and not use the neutral terminal.

Be sure the motor amp load is less than the amperage rating of the outlet and circuit and you should be fine.