all i can say is fuses are there for a reason...
they melt moments before the circuit does...
over rate the fuse size and the fuse wont melt
but everything else will!
multimeter is your best friend for this job (if suitable),
i agree on the short idea... and it could be possible
to have too small a fuse too - use car ammeter (30 amp) to see how much current the fan only uses, using a new circuit of course to test it.