Hi guys

I was wondering, even though this is not really related to a specific car problem, if someone could shed some light on electronics for me.

my 190E has an aux fan, which is electronic, and since my ac is dead, and will probably remain that way for a while, I wanted to hook up a switch in the cabin so I can turn on that fan manually.

I'm quite sure this will help the motor stay a bit cooler in hot summer traffic weather, plus it should not be too hard to do, I have all the components already,

BUT, I don't want to set anything on fire.

I know how the circuit should look like, this is not a problem, but my main concern is numbers, and how you go about figuring them out.

If I have a switch connected up to the battery which is then connected up to the aux fan, where would I place the fuse? What rating fuse should I use so that nothing gets damaged, and what gauge wire should I be using to do all this?

Would anyone be able to show me the math behind this? I have taken electronics, but only in theory, and even with my books I am not sure about figuring this out.

Any help will be greatly appreciated.

TIA

xp

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1985 190E 2.3L - a constant project.