Fan Wiring Help

[Þ² loc_h0]

I have a couple of fans that i have pulled out of some machines. One has three wires. yellow, red and black. and the others just black and red. What is the fan with the 3 wires for? is there a special use for a fan with the yellow wire? im thinking its for senory and speed adjustment. thanks for the help.

 

[ryuji]

yellow wire is for measuring rpm.. nothing more.. chop it off.. dont need it