Hi guys, I'm installing a manual radiator switch on a 93 Buick Century. The fan has two wires, solid black and black w/red stripe, and I need to know which ones are negative and positive. I don't have a voltmeter or test light.
hook them up to a battery, the position that makes it spin the right way is right. make sure to wire in a relay, fans draw alot of power and even if the switch is rated for it they tend to wear out fast
If all you are doing is installing a switch, it shouldn't matter which wire you use, but I would not do that if I were you. Justin is right about wiring in a relay. You don't want to wire in that much current draw into a switch inside the passenger compartment.