One is +12v, one is -12v, and the other is speed output.
Mark the wires 1, 2 and 3.
Attach wire 1 to +12V on the adapter. Attach wire 2 and then 3 to -12V.
If none work, or spins wring way, attach wire 2 to +12V then try wires 1 and 3 on -12V.
Repeat for wire 3.
If none work, you have a dead...