My Macbook has a fan speed that hovers between 0 and like 400 RPM. The macbook was recently torn apart and all the dust removed (this problem was exhibited before taking it apart). Trying to increase the fan speed using smcfancontrol causes the fan to go to 0 permanently. I tried resetting the SMC several times which worked in the past but didn't work now. I still believe it might be a software issue, but I'm not sure any other maneuvers to take. Otherwise I'll replace the fan but I'd rather not take the computer apart again.