MacBook Exhast Fan Speed - what is the max?

Discussion in 'MacBook' started by n1sni, Jun 25, 2010.

  1. n1sni macrumors newbie

    Joined:
    Jun 25, 2010
    #1
    Hello All,
    First post, so please be kind...

    I am trying to figure out if I have a dead fan in a customer's MacBook. The computer has an issue where it kept locking up. I tried cleaning everything inside (There was a bit of dust, but not a lot - especially between the fan and the heatsink... took it all out), replacing memory, and other diagnostic tools. No mater what I did, the mac would still freeze. So finally, I held it in front of my A/C unit. No mater what I did, it worked perfectly. Took it away, and within 5 minutes, the mac would freeze. So I started looking at software packages to adjust fan speed, and monitor temps. The CPU seems to get to 132ish degrees F before locking up according to iStat Pro (Which doesn't seem that high to me... odd). The part that I found odd is that i used smcFanControl to set the speed of the fan after the whole A/C test. The slider lets me choose up to 6500rpm, but the fan will ONLY ever go to 1795-1800rpms. Is that normal? Do I perhaps have a bad fan? I know that I will not normally run this at 6500rpms, but I am just wondering if the fan is dying/dead on me...

    Thanks!
     
  2. GGJstudios macrumors Westmere

    GGJstudios

    Joined:
    May 16, 2008
    #2
    Usually the fans run around 2000rpm. When a high temperature is reached, the fans don't necessarily spin faster. The higher temps usually must be sustained for a period of time before the fans spin up. The highest I've seen mine go is around 6000rpm.
     
  3. n1sni thread starter macrumors newbie

    Joined:
    Jun 25, 2010
    #3
    Ok... that's odd... plugged it in?

    Ok... so after all this testing, I noticed that the battery level was getting low... as soon as I plugged in the cord, the fan shot up to 6192ish RPMs!! Now if I unplug it, it stays at that speed... hmmm... let me test like this for a while...

    Thanks, I'll be back...
     
  4. Pax macrumors 6502a

    Joined:
    Dec 12, 2003
    #4
    Some thoughts

    - CPU shouldn't be hot enough to lock up, unless there is some bad solder or similar. 132 F is very normal for idle, pretty cool.

    - could be memory? You don't say what model you have, but on older Macbooks (pre-unibody) the memory can run quite hot which can cause lock up problems. Get iStat or something and look at memory back / memory controller temps.

    - try resetting the SMC, Apple site will show you how. SMC controls fan speed among other things

    - a bad or unplugged temperature sensor can cause the fans to run at full speed. Hardware Test (on the install disk) will detect a bad sensor. Note:- iStat doesn't "see" all the temperature sensors so it's worth running HW test.
     
  5. Blondie :) macrumors 6502a

    Blondie :)

    Joined:
    May 12, 2010
    Location:
    Prescott, AZ
    #5
    Indeed, resetting the SMC would probably be your best bet to start with. And then of course the hardware tests. Let us know what happens, I'm rather curious to learn what it is.
     
  6. JacaByte macrumors 6502

    Joined:
    Dec 26, 2009
    #6
    If it's the same for Macbooks as it is for Macbook Pros, 2000 RPM minimum, 6000 PRM maximum. I don't know why smcFanControl would show values different from the minimum and maximum, my experience is that it shows the proper values for the min and max.
     
  7. johnnyham macrumors regular

    Joined:
    Jun 18, 2010
    #7
    When you say it freezes up, do you mean the computer just shuts off or you get the spinning pinwheel? If it shuts off, it's more than likely heat-related. If it's just the spinning pinwheel, it's most likely a hardware issue. Placing it near the A/C unit may have less to do with cooling it off than just inadvertently placing something in the right place. Does the system still freeze if you boot up from an install disc? Have you tried installing a different drive and seeing if it still freezes up?

    Another opinion as to why it might be freezing up could be an issue with the hard drive. Disk Utility can tell you the S.M.A.R.T. status of the drive.

    The fastest my fan (mid 2009 Macbook) has gotten is 6197 RPM, typically if I'm transferring a bunch of files or using Flash. This keeps the temperature around 140ºF, although I've seen it hit 160ºF before. It normally idles anywhere between 1100 and 1700 RPM at approximately 130ºF. In my experience with Macs, this is pretty average.
     

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