12 Replies Latest reply: Feb 19, 2012 5:55 AM by Canman
Canman Level 1 (125 points)

Ok, here is the story, I had a video card problem with my imac and had an authorized dealer replace it.  The video problem is now corrected however when I got back the imac and turn it on, the fans run at full blast.  I am not impressed with the AD that they did not check this first but they are 2 hours away and don't want to do business with them anymore.


Most of the research I have done with fan problems are a result of HD changes,  I did not change the hard drive.  I still have the HD and SSD drive that came with the imac from apple so the hardware has not changed.


I also ran two fan software packages and both did not allow me to slow the fans down only set levels for them so that did not help.


When I look at Fan Control app, It shows regular temps for CPU, Internal DVD, GPU Heatsink, However it shows the HDD temp at 0 Degrees.  Meaning that it is not getting a correct temperate from the HD?  From what I read the sensor is built into the HD?


I have the imac open and all fans are running full speed, not just the HD fan.


I tried reseting the smc?  Wich is just shutting down and unplugging and rebooting.


This is what Fan Control Says.  It seems everything is running fine but because its not getting a temp from HD it goes into panic mode. 


Any Suggestions would be a great help?



Alos rand a hardware test with this result. 4SNS/1/40000000: TH0O-9.000  wich I believe is exsessive heat in harddrive.  This I don't believe as the whole insides is cool to the touch, activity monitor show no usage on cpu etc.  The HD is cool to the touch and works fine.  I only use this as a backup drive as I have the SSD drive as main.


iMac, Mac OS X (10.5.4), 16GB Ram
  • iCare Level 4 (1,765 points)

    Since the issue you experienced occurred right after having the system serviced I really think you should take it back to the service provider who did the work. The error indicates a sensor issue related to the hard drive. It may be a simple case of poor workmanship where they left something disconnected. If your system is still under warranty why risk voiding your warranty by opening your own system? I suggest finding another service provider if you're that unhappy with the one who did the work.

  • Canman Level 1 (125 points)

    True, However they are two hours away and like any lame shop these days they won't take responsiblilty for it.  Not impressed with this guys at all.


    Anyway, I have it taken apart, screen off.  Double checked all the connections for HD and sensors.  I can run it open because I have it hooked up to an extenral monitor.  I'm not sure if having the screen off would make the fans run.  But I think the temp sensor reading 0 is the clue.


    Does anyone know if the sensor is inside the hard drive?  If so I need to replace the whole hard drive?

  • iCare Level 4 (1,765 points)

    The answer to your question depends on which model iMac you have. You indicated you purchased it from Apple with the SSD drive option, so that limits it to the last two 27-inch models. There was some discussion on the boards about changes made to the hard drive sensor between these two models.


    http://blog.macsales.com/10146-apple-further-restricts-upgrade-options-on-new-im acs


    If I were having problems with a service provider who serviced my product under warranty I would either work with them or give Apple a call to intervene and get the issue resolved. I spent too much money on my iMac to jeopardize voiding the warranty.

  • Canman Level 1 (125 points)

    The imac is out of warrantee and I didn't get extended apple care.  Dumb on my part.


    Its the 27" imac i7.  mid 2011.


    Thanks for your input.

  • iCare Level 4 (1,765 points)

    If you have the Mid 2011 model iMac as you indicated then there is no way for it to be out of warranty. The Mid 2011 iMac was introduced in May 2011, which means that all of the Mid 2011 iMac's shipped so far are still under the 1 year hardware warranty. In fact, if you are under the 1 year warranty you can still buy the AppleCare Protection Plan if you want to.


    If you have the older Mid 2010 model then your system probably is out of warranty.


    Since you've been inside your iMac did you happen to notice whether there is a tiny two wire cable plugged into the connector end or the hard drive along with the standard SATA cables? The two pin cable is unique to each brand of hard drive, and must be properly plugged into the hard drive and the logic board. You can see a sample picture of the temp sensor cable at the URL below. If the cable is disconnected, damaged, or incorrectly connected then you will experience the fan ramp issue.




    Since you already have the iMac open please be careful. The power supply retains a charge for some time after it after the iMac has been disconnected from AC. I zapped myself once while experiement with an iMac, and it's not something I want to do ever again.

  • Canman Level 1 (125 points)

    Yes, I have that cable.  I am thinking that is the cable that gets the temp from the hard drive and send that info to the logic board.  I read about some people shorting out that? 


    It is possible I didn't put it back in the same way it was put in but it can only go back in two spots.  Top or botton of the slot.  I tried both.


    You could be right on the year, Apple told me it was out of Luck.



  • iCare Level 4 (1,765 points)

    There may be hope yet. Thanks for including the picture. I can see that you have the sensor cable attached, but I am concerned that it may not be attached to the correct pins.


    Each hard drive sensor output connector is different. Based on the picture it's hard to tell if the connector is installed properly. From the shape of the PCB on the hard drive it looks like a WD drive. If that's correct the WD drive should have an 8 pin connector next to the SATA connections similar to the diagram below. The two sensor wires (that are part of the 6 position sensor connector on the cable) should be connected as highlighted in green. The sensor cable, assu when attached to the hard drive will leave the left two pins open.


    Hard drive sensor WD.jpg

  • Canman Level 1 (125 points)

    wow, thanks for this pic.  Exactly what I am looking at.  I think I have it in the right spot, only variable would be white wire up or down.  Here is what it looks like now.



  • iCare Level 4 (1,765 points)

    We're running out of things to look at. The only other thing you can do is to verify that the cable is plugged into the logic board and that the pins and/or connector on the logic board aren't damaged.

  • Canman Level 1 (125 points)

    One thing I was thinking, The LCD panel does have a heat sensor.  For testing purposes I and using an external monitor.  If the LCD is not hooked up with that make the fans go turbo mode?  Like the having the HD hooked up wrong does. 


    Should I hook up the LCD in order to truly test?


    Also any idea about the idea what side should go up on the switch there is a gray wire and a black wire.


    Thanks again for your time and input.



  • iCare Level 4 (1,765 points)

    If any sensor is disconnected the fan(s) will ramp to protect the system. I made the assumption that your system was fully assembled. If you haven't already done so, reassemble the system and then test again. Your problem may be resolved, although it wouldn't explain why the fans ramped as soon as you brought it back from the service provider unless they had left a connector partially removed.

  • Canman Level 1 (125 points)

    good news, I reconnected the LCD and the fans didn't go to blast mode.  So it is possible the wires were not connected correctly or poorly in the first place.  But so far so good. 


    Fan control stil says 0 degrees Celius for the HD, but that could be the SDD drive as I don't think they heat up much.


    Thanks again for all your help.