The_Professor ...

I am in the process of replacing my blower motor, it seems that over time these wear out, and begin to pull A LOT of current, thus these fuse / melting issues. I realize it's cold where you are, but I would disconnect this fuse until you have fixed this issue. Moving to the external box is a good idea, but even doing so you probably need to consider looking into replacing the blower motor.

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Brent