Can you get to the connector on the fan? Check it for voltage.

That final wire you mentioned; what did you tap into? I hope not the ignition switch 'cause it's not rated for any more current than factory unless you use low current relays. Many people have jacked thier ignition switch this way. One of the symptoms is a malfunctioning AC fan. Sometimes it'll only work on high and other times it won't work at all.