I made this diagram as a one way to wire it, Using three relays if you got A/C, to be able to turn the secondary fan not just by the dual temp sensor, but also when A/C is on.

Having ammeter is not correct to feed them from battery, but from alternator, OR at some juntion point between ammeter and alternator

You can also feed the system with key in Ign1 ( run ) or straight from the main wring ( batt circuit ) and that will keepit working still with key off untill get the temp completelly down