Voltage drops when turn on electric fan

nm9stheham said

If the alternator is not putting out more than 12v at 1500 or 2000 RPM, then something is wrong with the alternator (like blown diodes) or the field wiring is messed up..

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Exactly what I said earlier OR IT IS TURNING TOO SLOW, meaning the pulley ratios, engine speed OR BELT SLIP is not turning the alternator fast enough

He has not field wiring "it's a one wire" I believe