67 Barracuda Heavy Electric Load

You are posting some confusing info

At some point you said something like "the wiring is stock" and then said "it has been replaced."

Then you showed the AMMETER and mentioned the VOLTMETER. Has the ammeter been converted to a voltmeter? Have you eliminated the bulkhead connector? Otherwise, what you showed is a FACTORY AMMETER All the current in the car except the starter motor goes through the ammeter. It was never meant for such things as fans

IF YOU ARE running this kind of current through a STOCK LIKE/ STOCK TYPE wiring system WHICH STILL RETAINS the bulkhead connnector (or at least AMMETER WIRING) you are in over your head "for trouble."

"We need more (specific) info

HAS the bulkhead connector been eliminated?

IS the wiring non factory or not?

HAS the ammeter been eliminated, and is what we are seeing a voltmeter conversion?

THEN WE CAN get into "how large is" the wiring etc etc.

READ THIS concerning ammeter / bulkhead connector/ undersized wiring problems.

http://www.madelectrical.com/electricaltech/amp-gauges.shtml