Ford supplies only two of the fuse/distribution panels. The coach builder supplies all others.
The early F53 has a "fuse box" located under/in the dash somewhere near the steering column. Fuse position (actually a circuit breaker) number 2 is for the windshield wipers.
There is a second Ford supplied box, the "power distribution box" located on the outside of the firewall (under the hood, so to speak) that contains additional fuses and relays for the more heavy current items like the horn, fuel pump, ignition, headlamps, etc..
Both boxes have fuse locations labeled "Body Builder Accessory Feed". These positions are where the coach builder fuses things that they add, such as those overhead fans.
I'll attach a scanned page from a 1994 manual that may, or may not, be of much help. The standard supplied manuals did not include detailed point-to-point wiring diagrams.