Internal fan.

[pilkenton]

My late 2009 21 inch I Mac has never had a problem. The internal fan never ran, until the other day. Now, after extended use, the fan turns on. The computer has been in the same spot since I bought it. Is this a sign that something is going wrong with it?

 

[AppleNewton]

install iStat and check the temperatures.

either a temp sensor is gone bad or the fan just needs tobe replaced.

they shouldnt be too expensive, best bet to find an authorized service provider for cheaper prices. apple stores may be fairly inexpensive.

 

[pilkenton]

I Stat

Will Istat let me know if there's a problem? I've always had an external fan blowing on the back of my Mac at low speeds. If I turn the fan on high, the internal fan eventually turns off.

 

[orangezorki]

It could just be dust causing it to run a bit hotter, or even your heating turning on for the winter, causing the ambient temp to go up. Or even a reduction in ambient noise causing you to hear the fan for the first time. You could open it up to clean out the dust bunnies, clear out unnecessary apps that might be stressing the machine, or just live with it if everything is working fine.

David