14 Replies Latest reply: Jan 17, 2013 3:56 AM by Markcw98a
markcw98b Level 1 (0 points)

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 Level 6 (10,625 points)



    you can browse http://www.ifixit.com/Browse/iMac 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 Level 3 (985 points)

    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.
  • markcw98b Level 1 (0 points)

    I appreciate the responses from both of you.   I have tried to find AHT and have also tried getting it to boot off the internet.  I am likely doing something wrong, but have been unsuccesful so far.   My iMac has been fine since that first occurrance.  I have been turning it off at night (vs sleep).   I have found a video on the internet that shows how to open it up and may try that to see if there is an airflow issue.   Other than that, would really like to run the diagnostic.   Will try it again later this afternoon.  


    My original Mac had Leopard installed on it.   I installed Snow Leopard and put Lion on it in Dec.    I tried the recovery disc that was installed with Lion- but see no option to start AHT- only start a new install.   I also tried the SL install disc- same deal.   I would think I would not have to go back to the Leopard disc- again, suggestions welcome.   Thanks. 



  • markcw98b Level 1 (0 points)

    By the way- I mis-typed the age of my iMac.  It is an early 2009 (not 2007).   I bought it in April of 2009- at least that is the date of the picture of me walking out of the Apple store with it:)   Sorry for the mistake


    Oh- and I downloaded a widget for it that monitors the system, including temperatures.   It is called iStat Pro.   Nice app.   The highest temp I see is the Northbridge at 62 degrees.  No idea if that is normal or not.  



  • rkaufmann87 Level 9 (53,510 points)

    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.

  • markcw98b Level 1 (0 points)

    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?).  


    Thanks in advance for your help. 


  • rkaufmann87 Level 9 (53,510 points)



    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.

  • markcw98b Level 1 (0 points)

    Thanks for your suggestions.   I don't think my last post was clear, so let me clarify. 

    1-  My iMac seems to be running fine after my initial shutdown and restart (see earlier post).   The fan is running normally.   So- repeating the SMC reset is not needed- it seems reset already.  


    2- I am unable to get AHT to run using the Hardware test instructions.   The instructions assume you have AHT loaded somewhere or that it is loaded via the internet.   It does not load via the internet.   And- I have shut down the computer and rebooted with the original gray applications disk and the disk is ejected and the computer boots up in Lion- even with D pressed the entire time.  


    So- I am unable to load AHT and unable to run it.   I would like to run the diagnostic but have not gotten instructions on how to do that.   HT1509 does not tell me how to run it with a computer that originally had Leopard installed but now has Lion.   The Leopard install or app disks will not stay in the drive- they eject.   If it helps, I do have a version of Snow Leopard on an external drive that I can run.  


    Suggestions welcome.   Thanks.  


  • rkaufmann87 Level 9 (53,510 points)

    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.

  • markcw98b Level 1 (0 points)

    Thanks again for the response.   Regretfully, still no AHT.   I have an early 2009 iMac (not the early 2007 I stated incorrectly in my original post) and the instructions are similar to yours.   I disconnected everything (except keyboard and mouse)- held the D key down before restarting- got the gray screen- then I waited for about 1 min before seeing the apple come up- it booted into Lion.


    Today I am going to try to do this with Snow Leopard- maybe it is a Lion quirk. 


  • markcw98b Level 1 (0 points)

    Well- today I walked into the office and the fan was on full speed again.   I guess whatever is happening, it takes a about 1.5 weeks before it happens again.   I neglected to use the temperature program before resetting SMC (maybe next time) but the Mac did not feel hot (fan on full, I would think not).   After the reset, all is back to normal.  


    Anyway- thought I would post.   I plan to do a thorough cleaning in the next few days- if I can figure out how to open the iMac up.   Per one of my posts, I have found a video that shows me how- so we will see what happens.  


  • markcw98b Level 1 (0 points)

    Yesterday I opened my iMac up and cleaned it out.   I followed instructions that I found on You Tube.   There really was not much dust blocking airflow, that I could see.   But, I am hopeful that this will solve the fan issue for the time being.   Taking it apart was not that hard.  I had the most challenge getting the camera cable plugged back in.   Plenty of screws- keep track of where the longer ones and shorter ones go.  


    You Tube link:   http://www.youtube.com/watch?v=2YsCTNVEYt8


    Thanks for all the responses.  


  • qqallan Level 1 (0 points)

    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 Level 1 (5 points)

    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.