...I agree with Panteradoug and JB1490...could be a Isolating Circuit Breaker, for ALL Systems. And, Who Installed the Custom 'Fuse Block', that is suspect, could be one or two wires Not connected correctly. I, also, had the problem with the AMP Gauge, 'Very' Loose connections!! Long since, removed, Cables spliced Together with a Bolt!, Shrink-tubed with INDUSTRIAL/Thicker Shrink Tubing, Two Layers...and a VOLT Gauge added. You need to Learn HOW to Use the VOM. Check ALL Grounds, Including the 6-8 wires, To a Stud, just above Your left Knee, under the dash. And check the Ground to the chassis, AT the Battery, as others have suggested!!. The Ignition SWITCH, could be 'Shorting-out', usually Burned-Out, Internally!!!
I still think the 'One' Fan was wired to the Ignition Circuit!! Check that 'White' Junction Block just above the Steering Column! That would also mean...the ignition, Also, was wired to the ACC position of the Ign. Switch.
...Get out the Volt Meter and start Investigating!
Good Luck!
MJ
P.S. Just a Thought, what about the 'Major' Ground strap going from the Chassis to the TAIL of the ZF Gearbox?? That 'Woven' Thing is always seen corroded and Rotting! That strap is the ONLY Link Grounding the Engine to the Battery, through the Chassis. And Last, the Headlights DO NOT work when the Ignition Switch is TURNED-OFF!!