How maybe a better understanding of why it blows fuses is better so I know what to look for?
One of the high school subjects I teach is "Automotive Electrical Systems", so I get this type of question all the time. Simply put, a fuse is in the circuit to protect wires, and prevent fires. When a circuit is designed at the factory, engineers figure how much current a piece of electrical equipment needs in order to operate properly, and they use a wire for that circuit that can carry the current safely. For instance, a heater blower motor might need 15 amps, which would require about a #14 wire, or maybe a #12 to supply the current without overheating. Add a little overload capacity for surges, and you'll probably find a 20 amp fuse in that circuit. If a short happens, the fuse will blow before the current goes high enough to overheat the insulation, melt it, and possibly start a fire. The fuse is NOT there to protect the motor- - - - -if it shorts out, the fuse isn't going to prevent the failure. Once a part fails, or an unintended ground happens like a wire rubs through its insulation against the frame, etc., the fuse prevents a disaster. Fuses are sized to match tne wire they protect- - - -if you install a big fuse to handle an overloaded circuit, the wire becomes the fuse and it will overheat or burn instead of the fuse. Lots of vehicles have burned down because someone bypassed a fuse, or used a too-big one after adding extra accerssories to a circuit with a too-small wire to handle the current draw, then upping the size of the fuse.
Jerry
