I aquired this Toshiba A45 S121 with a known heat problem. Got a really good deal. After a while the system will shut down. After cooling off it always starts up. I believe the (CPU)cooling fan blows for a while but then seizes up or something. It is real hot where fan and fins are. Anyway, I disassembled the machine and removed fan. Now I want to test it on the bench. I used a plug-in-the-wall 12V 800ma DC source and stripped back the red and black wires (so I can restore if necessary) and applied voltage and fan does not move. Polarity is correct. There is a third wire coming from fan, it is grey. I'm not sure what that's for, I suspect it is a temp sensor or control wire. I don't want to buy a new fan until I'm sure it is the problem. Can someone straighten my head out. Maybe my voltage source is not good enough or the grey wire needs something??? Thanks!