So I took my new to me 98 Cherokee wheeling last weekend, and found out the hard way the electric cooling fan doesn't work

When I got home further inspection concluded:

-Pulled the cooling fan relay, stuck a meter down the pins. +12v power at 2 of 4 pins for the coil and power - all good.
-Pulled the fan plug and stuck power and ground down it - no go. Took the fan motor apart, unstuck the brushes from the brush holders. Tried power to it again - works good.
-Tested fan by turning on A/C. -Fan does not come on.
-Pulled relay and put it back in. When putting it back in the fan gave a small kick then turned off. Seems there isn't enough power to hold the relay in.
-Swapped relays - Same thing
-Started pulling fuses because it's easy, just to see if one was half burnt or corroded causing low voltage. The 15 or so (can't remember) unmarked fuses in the box under the hood was where I started. When I pulled the 15amp in the row closest to the front, 2nd from the passenger side, the fan comes on full force and works perfectly??

Does this make sense to anyone? And does anyone have a service manual that tells you what these fuses are for that can inform me what this one does? And perhaps someone can point me to where I can can buy my own repair manual?