Read here: 
http://www.njfboa.org/forums/showthr...light=autozone
If you have ruled out bad fans, bad wires from relay to fan, primary power circuits & relays, then that leaves you triggers & trigger circuits.  But I am not sure you have actually done this.
*Your car might be ECM triggered, you'll have to find out.  Else a fan switch.
*The trigger circuit wires are bad (relay to switch/ecm).