[petek]

*IF* the harness wiring is consistant with the fan (probably 14 awg, maybe 12 awg) then going to a 30 amp fuse won't hurt a thing and will still protect the wiring. If it was me, I'd go with a 25 amp fuse and see if it holds ok.

Another option would be to use a 20 amp circuit breaker rather than a fuse. Most automotive circuit breakers work by passing the current through a bi-metalic strip. As more current is drawn the strip heats up. If too much current is drawn the strip is heated to the point that it breaks contact. The neat thing about thermal circuit breakers is that you don't have to worry about in-rush current (as the current doesn't last long enough to create enough heat to pop the breaker).

I've only once blown a 20 amp fuse with my fan. The fan had stalled (insulation holding the fan blade) and the fuse blew. Not having any 20 amp fuses on hand, I replaced the blown fuse with a 25 amp fuse. I don't expect the fuse to blow again ... unless I stall the fan again!