2009 24" iMac Fan is going bad

Hi,

One of the fans in my iMac is going bad. I know there are three. Anybody know how to figure out which one needs to be replaced? Is there one that fails more often than the others?

Location-wise the noise appears to be coming from the left or center (when facing the monitor).

I've opened it up and cleaned the two visible fans, but still have the problem. I'm hardware savvy and plan to replace it myself. Just need to know which one!

Thanks for your help.

-J

The three fans are: CPU, Hard Drive, and Optical Drive. So, by the process of elimination which two visible fans did you clean?

If you suspect one fan isn't working, download the free iStat Pro Dashboard Widget which will give you a read out of all three fans. Also gives you temperatures.

chscag said:

The three fans are: CPU, Hard Drive, and Optical Drive. So, by the process of elimination which two visible fans did you clean?

If you suspect one fan isn't working, download the free iStat Pro Dashboard Widget which will give you a read out of all three fans. Also gives you temperatures.

Click to expand...

I cleaned the CPU fan (left side) and the Optical Drive fan (right side). But who knows if that did anything. I'll download the iStat Pro and report my findings. Thanks for your response. -J

Update: Fan speeds are attached. I have no frame of reference as I don't know what the speeds should normally be, but maybe someone does.

Your fan speeds and temps are different than mine, however, my iMac is a mid 2011 model and yours is a 2009 model. But, the speeds you show and the temps do not seem out of norm. Why do you suspect one of the fans is going bad? Is it noisy?

chscag said:

Your fan speeds and temps are different than mine, however, my iMac is a mid 2011 model and yours is a 2009 model. But, the speeds you show and the temps do not seem out of norm. Why do you suspect one of the fans is going bad? Is it noisy?

Click to expand...

Yes. Intermittently, noisy. It's pretty strange as it (the noise) won't happen for a few weeks. Then just tonight it flared up again. Now it's quiet and sounds normal. I will probably have to go with my gut and replace the CPU fan. Thank you for comparing your stats. -J