One thing I've always noticed about my PowerBook G4 - only one fan seems to work.

Discussion in 'PowerPC Macs' started by Xandros, Feb 28, 2012.

  1. Xandros macrumors regular

    Sep 19, 2010
    My PB, the 15" 1.67 hi res model, currently in disarray with the battery not charging, has had it's ups and downs over the years. But one thing I've noticed since I got it in late 2007 is the fact that I can only hear one fan spinning up in times of hotness. However when I first pulled the thing apart to repair something in it, I discovered it actually has two fans.

    The one on the left (left as in as you look at the keyboard) definitely spins up and makes that signature whirring sound, but I don't think I've ever heard the one on the right making any noise at all. I've even stuck my ear to the vent on the back of the powerbook when it's been running hot and, while I can hear airflow from the left hand fan I can't from the right.

    That's not to say the right hand fan isn't running at all of course, it could just be whisper quiet and the one on the left is the only one that ever gets powered right up to make that noise (the case does always seem to get a bit hotter on the left than it does the right). I do wonder though if I've got a dud fan in it.

    Has anyone else here who has one of these PB's ever noticed this same thing or can they can definitely hear both fans powered up when the system get's hot? If I end up having to fix my DC board to rectify my battery charging issues I figure I might as well fix that fan too if it truly is broken, it might make the system cooler in future and thus make components like the DC board and the Mac overall last me a lot longer.
  2. eyoungren macrumors Core


    Aug 31, 2011
    ten-zero-eleven-zero-zero by zero-two
    I think the second fan only comes on during extreme temperatures. I have two 17" Powerbooks, both with two fans. I have only heard the second fan come up once or twice on my 1.67Ghz. At the time the Mac was on a couch during summer and the processor was pegged at 100% CPU for an hour or so. Temps were in excess of 130 degrees which is not normal for this PB as it usually operates around 100-118 (118 being where the first fan will kick in).

    My 1Ghz Mac I've only heard the second fan come on once. Again, in an extreme temp condition. Normally that Mac operates between 130 to 140 degrees and the first fan kicks on at 140. Even with high CPU loads though the first fan has always been able to kick the temp back down to about 132 or so.

    You might look into getting iStat menus. It's got a Fan option and you can see what RPMs your fans are doing.
  3. Xandros thread starter macrumors regular

    Sep 19, 2010
    Well as long as it's not dead that's OK. I do actually tend to avoid using computers in hot temperatures but being in the Uk that rarely ever happens lol. Thanks for clearing that up for me at any rate.

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