Previous 1 2 Next 16 Replies Latest reply: Nov 21, 2013 2:07 AM by danielemion
T. Lange Level 1 (10 points)

My iMac doesn't turn off in the normal way any more. The system shuts down and the screen becomes black, but the fan keeps on running. And it deosn't stop! The only way to completely shut down everything is to hold the powerbutton. I don't think that that's a proper solution.


I already have reinstalled Lion, but the problem is still prensent.


I've got this iMac for around 6 months now, but this problem occured around 2 weeks ago. Before everything has been all right.


I don't know what to do. Please help.



iMac, Mac OS X (10.7.3)
  • Barry Hemphill Level 8 (37,327 points)



    Try resetting the SMC.



  • T. Lange Level 1 (10 points)

    Thanks for your fast reply! :)


    But unfortunately resetting the SMC didn't have any effect on the behaviour of my fan. :/


    Do you have any other suggestions? :)

  • Barry Hemphill Level 8 (37,327 points)

    There is one more reset that I should have mentioned...


    Try resetting the PRAM.



  • T. Lange Level 1 (10 points)

    That didn't work also. :/


    But I recognized something: I started my mac with "cmd"+"r" and chose the repair section. After no problems have been found I shuted down the mac from there by clicking the apple and "shutdown". Surprisingly the mac turned off completely! No fan running any more.

    After I started the mac again in the normal way and then shuted it down again the fan stayed on as before. :/

    There seems to be a program or something changed, that keeps the fan up running. Do you think that an antivirus program might help?


    I'm afraid I will have to reinstall the whole OS and start all over with everything. :/


    If you know another solution, that would be great!


    Thanks for your help!

  • WZZZ Level 6 (12,875 points)

    I'd try running the Hardware Test


  • Barry Hemphill Level 8 (37,327 points)

    Do you think that an antivirus program might help?

    Absolutely not!  There are no documented viruses that affect a Mac running OS X - none.


    What I would do next would be to look at the log files (utilities>console) to see what is going on.  Then I would look at the activity monitor (when the fan is running after you try to put it to sleep) and see what processes are active. (utilities>activity monitor).


    I would also run repair disk from your software install DVD.



  • Frank Cioffi1 Level 1 (0 points)

    Hi Thomas,


    Did you ever figure this out? I have the same problem with my 2008 iMac.





  • T. Lange Level 1 (10 points)

    I think the only thing I did was reinstalling the OS several times. Unfortunately that was very time consuming for me because my internetspeed isn't that fast and I wasn't able to create a system USB-Drive. And, of course, I didn't make time machine backups sothat all my data was more or less lost. After that I immediately bought 1,5 Tb hard drive and set it up as my time-machine-backup-drive. Even though the problem with the system didn't occurs again - luckily - that extra hard drive turned out to be very helpful anyway. In my case: I was editing a video, saved the file, later opened the project again and realized that I did something completely wrong. With the backup I was able to go "back in time" and simply restore the older file ... . But in fact that's another story, sorry for rambling on. xD

    I hope that that helps you even though that's no proper answer to your question. :/


    P.S. Of course at first I tried the methods that were recommended above. They didn't help me, but maybe they'll help you. ;)



  • pmorandi Level 1 (0 points)

    I'm having the same problem with my 21'' imac (new in Dec 2012). After shutting down the fan comes on loudly. I need to unplug to get the fan to turn off.  When I plug back in (before turning the machine on) the fan comes on again.  After sleeping for a while the fan also turns on loudly.  I talked to Apple Care for several weeks, and finally got a new machine.  The new one is doing exactly the same thing.

  • TMacTeague Level 1 (0 points)

    pmorandi: did you ever make any progress or headway on fixing the fan issue?  I have had a frustratingly simialr experience.  Purchased a new 27" iMac in early January.  The computer did what you have discribed.  Aftert taking it to the Apple Store, they eventually replaced it.  Now I have a second iMac that is doing exactly the same thing. Seems so odd that people are having multiple instances of the same thing, yet I've found very little mention of this issue on the boards.  Any new news or findings you can share?  Many thanks.

  • pmorandi Level 1 (0 points)

    No I haven't resolved the problem. The head of my university's Apple store is looking into it, but nothing to report yet.  Since I've had two new imacs with the same problem I'm thinking this is a systematic problem.  I am also curious that I've seen so little reports on the web about this problem.

  • aellul Level 1 (0 points)

    hi all


    i have solved this quite some time ago.


    in my case it resulted in a sensor not properly fitted in on the logic board.


    i suggest taking your mac to a specialist and tell himto check the sensors on the logic board.





  • simonna Level 1 (0 points)

    Did anyone have any luck, I have taken my IMAC into the store twice now.  First time to have the fans replaced and the second time the mother board according to the technician, the only thing left is to replace the computer. Today its just started again !!! Sigh and our first Apple, its not a nice experience.

  • WZZZ Level 6 (12,875 points)

    Apple's policy is usually to replace at the third ocurrance.

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