iMac CPU Fan problem!

[faneos]

When I start my iMac CPU fan run at full speed istat menus shows 0 rpm temperatures and and everything else seems normal I did a SMC reset problem stays I tried a SMC reset again and i will leave the machine off all night and i open it in the morning anyone have an idea whats wrong?

 

[ivoruest]

Either your iMac is clogged with dust or the fan broke. Take it to Apple Store.

 

[faneos]

I am unemployed now no money for apple store.There is a chance of defected cpu fan or software related error or anyone has an idea??

 

[Dadioh]

I am unemployed now no money for apple store.There is a chance of defected cpu fan or software related error or anyone has an idea??

It may be the PRAM that you need to reset, rather than the SMC. See instructions below. Basically unplug power cord, hold power button on for a few seconds, release power button, plug power cord back in, and hit power button to start. I believe that fan controls are stored in PRAM.

http://support.apple.com/kb/HT1379

 

[faneos]

I read a solution to remove the motherboard battery to reset it what your opinion ?

 

[Dadioh]

I read a solution to remove the motherboard battery to reset it what your opinion ?

I believe pram reset achieves the same thing and you don't have to open up the iMac. I assume the idea of removing the motherboard battery is so that the info concerning the fans and temp sensors is cleared. Pram reset does that.

 

[lexvo]

I had a similar problem, turned out that the temperature sensor of the HDD was broken (even though iStat reported CPU fan). The HDD needed to be replaced to fix this (luckily I have AppleCare).

 

[GGJstudios]

It may be the PRAM that you need to reset, rather than the SMC.

PRAM/NVRAM has nothing to do fan issues. Resetting it will not help. Only resetting the SMC addresses such issues.

Mac OS X: What's stored in PRAM
When to reset NVRAM or PRAM​

 

[Dadioh]

PRAM/NVRAM has nothing to do fan issues. Resetting it will not help. Only resetting the SMC addresses such issues.

Mac OS X: What's stored in PRAM
When to reset NVRAM or PRAM​

My mistake. Could have sworn it was PRAM I was resetting a while back when troubleshooting a fan issue on my Mac Pro. But then again I almost always reset both pram and smc when working on an issue.