Fan and gauge issues

A slo-blo fuse would be best w/ fans since the brief starting surge current is much higher than the steady-state current. True of all DC motors, when stalled the only thing limiting the current is resistance of the armature, which will melt if stalled too long. Once turning, it generates a "back emf" which greatly reduces current draw. But, you don't need to design it, just copy. If JY fans, lookup the wiring diagram for the vehicle you robbed and use an equivalent fuse.