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Overheating iMac (early 2007 24 inch)

2220 Views 14 Replies Latest reply: Jan 17, 2013 3:56 AM by Markcw98a RSS
markcw98b Calculating status...
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Jan 23, 2012 8:15 AM

Hi all.   I have an early 2007 iMac that has been working great since I bought it in early 2008.   I currently have Lion loaded on it.   I typically let it sleep when not in use, but lately have been keeping it on since I use it to watch movies on Apple TV.   Today I walked into the office and the internal fan on it was at full speed.   The iMac was working fine.   I turned it off for a few hours and turned it back on and am using it.   It seems to be fine- been on for 45 minutes with no high speed fan noise.   I do hear the normal speed fan runing.  


Should I be concerned?   I would like to clean dust out of it.   I am guessing that may be the culpret.   Are there some tutorials somewhere that instruct you on how to take it apart so I can do that?   It is out of warranty and I do "dabble" with PC computer repair.   Any diagnostics I could run to see if I have an overheating issue? 


Has this happened to others and are there suggestions.    Thanks.  



iMac, Mac OS X (10.7.2), 2009 iMac, leg iPhone, iPad2
  • durignieux pierre Calculating status...
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    Jan 23, 2012 9:21 AM (in response to markcw98b)



    you can browse for imac manual , be carrefull , need torx tool but not realy dificult to desassemble


    but first try an AHT test ( locate on grey dvd come with your imac ) , coud be a faultly sensor or other part


    take care off your DATA , data back up sould be a good idea




  • Eric Fauque Calculating status...
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    Jan 23, 2012 9:32 AM (in response to markcw98b)

    Before you go and open the body of your iMac I recommend you try this:


    Run Apple hardware test

    To see if it finds anything wrong.



    • Shut down the computer.
    • Unplug the computer's power cord and all peripherals.
    • Press and hold the power button for 5 seconds.
    • Release the power button.
    • Attach the computers power cable.
    • Press the power button to turn on the computer.


    • Shut down the computer.
    • Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
    • Turn on the computer.
    • Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
    • Hold the keys down until the computer restarts and you hear the startup sound for the second time.
    • Release the keys.
  • rkaufmann87 Level 8 Level 8 (40,500 points)
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    Jan 25, 2012 8:20 AM (in response to markcw98b)

    AHT is on the origninal Install disc that shipped with your computer, that is the ONLY place you can get. If you cannot find your discs then you will need to call AppleCare and they can replace them for a nominal charge.


    I also agree that it's a bad idea to open the computer at this point. I would recommend AHT but first do the SMC reset as you were instructed.


    ERIC, thanks for copying my SMC & PRAM instructions, glad you have found them useful.

  • rkaufmann87 Level 8 Level 8 (40,500 points)
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    Jan 25, 2012 8:57 AM (in response to markcw98b)



    Thanks for the response.   I did the SMC reset, as instructed.   I don't see any obvious change.   (Did not realize that it was the System Management Controller until I looked it up). 


    I have the original Leopard install discs (one is OS and one is Apps).   How should I proceed?   The last time I tried it, it either remained in the gray screen or ended up booting into Lion.   Or, with the install disc and holding C- it gave me an option to reload the OS (do not want to do that, right?).  



    I would do the SMC reset a second time, it won't hurt and may help.


    Regarding AHT please read the Hardware Test instructions carefully. Run the test in Extended Mode!  If no errors appear after the first pass then run it another 2-3 times to be sure. Note: Each pass will take approximately 30-60 minutes.

  • rkaufmann87 Level 8 Level 8 (40,500 points)
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    Jan 25, 2012 1:02 PM (in response to markcw98b)

    Now I see why you are having problems. The instructions for AHT have changed, you can find the proper instructions in your owners manual, I'd refer you the correct instructions however I have no idea what  year iMac you have. To locate the correct manual navigate to



    locate your model iMac and then once you have found it do a search (Command F) and type "hardware test." For example in my late 2007 machine the manual says:


    To use Apple Hardware Test:

    Disconnect all external devices from your iMac except the keyboard and mouse. If you have an Ethernet cable connected, disconnect it.


    Restart your iMac while holding down the D key.


    When the Apple Hardware Test chooser screen appears, select the language

    appropriate for your location.


    Press the Return key or click the right arrow button.


    When the Apple Hardware Test main screen appears (after about 45 seconds), follow

    the onscreen instructions.


    Apple Hardware Test displays an error code if it detects a problem. Make a note of the error code before pursuing support options. If Apple Hardware Test doesn’t detect a hardware failure, the problem may be with your software.

  • qqallan Level 1 Level 1 (0 points)
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    Jan 17, 2013 2:46 AM (in response to markcw98b)

    Mark, I'm having a similar issue as you described so I'm curious to hear if your approach worked. Did the iMac clean-up sort out your problem?

  • Markcw98a Calculating status...
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    Jan 17, 2013 3:56 AM (in response to qqallan)

    For what it is worth, I have not had any further issues after I opened up the Mac.  I have also set my Mac up to automatically sleep at night- just to minimize usage.  It is on every day and gets moderate usage.  I hope this works for you.  




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