ALRIGHT, I WANTED TO KNOW THE ANWSER TO THIS QUESTION AS WELL.
I HAVE THE SAME FANS BUT 4" IN/4"OUT 12VOLT.
I CURRENTLY HAVE NO USE FOR THEM BECOUSE OF WIRING THEM UP BUT,
I GUESS IF YOU HAD A AC TO DC ADAPTER/CONVERTER IT WOULD WORK.
HERE'S A LINK TO WHAT I'M TALKIN ABOUT
http://cgi.ebay.com/New-AC-DC-Conver...QQcmdZViewItem

I GUESS YOU WOULD HAVE TO SPLICE INTO THE PLUG THAT GOES INTO THE Cigarette Lighter Socket.
I:E CELL PHONE CHARGER

LIKE I SAID, I DON'T KNOW, BUT IT'S AN OPTION IF YOU ARE DEAD SET ON USING THE 12V FAN,
DO YOUR RESEARCH BEFORE DOING THIS BECOUSE I DON'T KNOW IF THIS WILL WORK OR JUST CAUSE MORE TROUBLE
I WENT OUT AND BOUGHT DIFFERENT FANS$$$$$$

SOMEONE THAT KNOWS ABOUT AC/DC CURRENT WILL BE ABLE TO ANWSER THIS QUESTION MORE THAN ME