In you ACAD drawing do the following:
File > either Page Set Up or Plot > Plot device folder > Plotter Configuration: select CutePDF Writer > Plot Style Table: select acad.ctb and Edit > Plot Style table Editor : from property window select black > save and close > Plot Dialog Box > Plot Setting folder: do full preview to double on black color of drawing > OK > drawing will automatically be saved in PDF format in black color. Note you must load CutePDF Writer in ACAD; CutePDFWriter is free of charge from internet.