1999 Chevy Tahoe Fan Switch on Dashboard

I'd use jumper wires for the blower motor, use inline fuse. Black wire is ground, the other voltage. If the jumper wires get too hot, I suspect a faulty blower motor. There could be other issues, I can't be sure of the problem without testing. Come off the battery with jumpers one for votage, the other ground, use 25 amp fuse, 12 gage wire should work. As far as testing, the safety issue is your responsibility.