electric fan help please !

okay wll im at the final stages today ! and everything is toghter and Done just need some help on my fam ,,, so i havesome kind of electric 16'' fan i got at a car show its a knock off but it is 2800 cfm fan and im un sure of the amps and voltage of the fan , i already burnt a switch up from the fan its a 12 vol 20 switch and i have the flex a lite themerl switch kit i hooked that up but any one have a clue if it just runs posative posative or it needs a ground ?