Unibody 2008 MBP Fan - On and Off!

Discussion in 'MacBook Pro' started by dirkph, Dec 2, 2011.

  1. dirkph macrumors member

    Nov 7, 2008
    I know there are a ton of these threads around, but none of them seem to have a real solution the problem I have.

    My fan on my late 2008 MBP keeps turning on and off constantly (in 1-2 second intervals, but sometimes it fully stays on). I don't know if this is the same problem described as "fan noise" in other threads, but I've tried resetting the PRAM/SMC and clearing the print jobs.

    Nothing really seems to work.
  2. GGJstudios macrumors Westmere


    May 16, 2008
    Are you sure they're turning off, or just returning to their normal speed? iStat Pro will give you accurate readings of your fan speeds, temps, and other things.

    Your fans are always on when your Mac is on, spinning at a minimum of 2000 rpm (for MBPs) or 1800 rpm (for MBAs, MBs and minis). They will spin faster as needed to keep temps at a safe level. If they're spinning up without increased heat, try resetting the SMC. PRAM/NVRAM has nothing to do with these issues, so resetting it will not help. Also, make sure you don't block the vents, which are located at the rear, near the hinge.

    Learn about the fans in your Mac

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