Macbook ('08 model) fan is spinning wildy all the time

Question

My Macbook (model MacBook2,1) spins the fan all the time, running ~6200 RPM constantly.

The CPU temperature is only 64 to 66 degrees celcius, which should be normal temperature. The fan should be running around 2000 RPM with this CPU temperature (or it common before the problem).

There's no load on the CPU and I have tried to reset SMC (as was recommended in Apple Support website). I tried to air duster to blow and clean the air vents, but no dust came out.

What could be the problem? What could I try to reduce the fan speed and the noise?

I didn't have any fan control software before, but installed smcfancontrol couple of days after the problem appeared. The software didn't make any difference.

Answer 1

I've found that SMCFanControl doesn't work reliably, and I use Fan Control.prefpane. It seems to work much, much better.

Answer 2

I also have a Macbook2,1 and the fans will crank up to 6200 RPM at the slightest load on the CPU. Since you seem to have smcFanControl, try typing this into terminal.

/Applications/smcFanControl.app/Contents/Resources/smc -k F0Mx -w 3e80

This should force your fan speed to stay under 4000 RPM. To get your fan speed back to normal, substitute 3e80 with 60e0.

Getting the value to input is a little complicated. 4000 * 4 = 16000. Plugging 16000 into a decimal -> hex converter results in "3e80". Likewise, 6200 * 4 = 24800 = "60e0".

Hopefully this helps; it's what I do. (Probably isn't too good for the computer though.)