MacBook Pro Fans Not Speeding Up

Discussion in 'MacBook Pro' started by Zane808, Jul 17, 2012.

  1. Zane808 macrumors newbie

    Jul 17, 2012
    Today, i began to notice that my MBP was running a bit slower than usual. After a couple hours of use, I also noticed it was running a lot hotter than usual. My laptop was running at 170F with only 30% CPU usage. I didn't make too much of it, and considered it an anomaly. Later on in the day, I noticed began to realize that my fan was running a lot slower than usual at higher temperatures. It was only running at 2000-3000RPM regardless of the temperature of the laptop or how much intensive activity I was doing.

    My first thought was "Oh great, the fans must be broken and I'll have to bring it into a shop and go through all that again...". I just had my fans die on my old MacBook, and I didn't want to deal with this again. To test the fans, I downloaded smcFanControl and manually set the fans to run at 6200RPM. Sure enough, manually setting it to 6200RPM sped up the fan. Now I knew that the fans themselves were working and could reach the higher speeds.

    What next? I tried a restart. Nothing changed.

    What now? Well, I obviously knew that smc involved the fan/temperature control, and I could reset it. So I did that. I reset my smc. Still no change.

    I started playing around with the fans using smcFanControl and noticed that no matter what minimum speed I would set it to at what temperature, it would always go with the minimum. If it was 5000, it would use 5000. If it was 6200, it would use 6200. If it was 2000 at 190F, it would use 2000.

    What should I do from here? Where should I go? If it was easy for me to get to an Apple Store I would just go there, but transportation is an issue and the store is a ways away, so I'd rather fix it on my own. Obviously, the fans can go up to the normal 6200RPM, but they won't for some rason.

    Other info:

    - All temperature sensors are working and seem to be reporting accurately

    - There has been no physical damage to it lately. No spills, drops, or other impacts.

    - It's a 13-inch, Late 2011 model
  2. Zane808 thread starter macrumors newbie

    Jul 17, 2012
    I've heard that fan sensors don't use the same temperature sensors that iStat gets data from. Is this true? If they're dead/not working, is there any way to check? Also, would there be anyway for the fans to just run on the same sensors that iStat uses to monitor temperature?
  3. TUSR macrumors newbie

    Jul 12, 2012
    190F and your fans are not running at ~max speed automatically. Thats a huge red flag in my books. You have exhausted my ideas what to fix though.

    I know there are different temperature sensors inside, any idea what part is 190F?
  4. Zane808 thread starter macrumors newbie

    Jul 17, 2012
    Oh, yes, the CPU was 190F. The base was about 105F at those high temperatures(a bit higher than normal), and so was the HD. The heat sink was around 150F, and the mem modules were about 140F and 120F.
  5. Zane808 thread starter macrumors newbie

    Jul 17, 2012
    Found a temporary fix for this issue. Since the temperature sensors and fans were working, I wrote my own fan controller. It relies on smcFanControl to actually set the speed, and Temperature Monitor to get the CPU temp.

    If anybody out there ever encounters this issue, the above link is the source of the fan speed controller. It may require a few tweaks, and was written in Python. Still has a couple lines of debugging code that prints info that will allow you to double check its calculations.

    I'm still looking for a permanent fix to this issue.
  6. negativzero macrumors 6502a

    Jul 19, 2011
    I suggest trying to reset your SMC and see if that helps.
  7. Queen6 macrumors 603


    Dec 11, 2008
    Putting out the fire with gasoline...
    First thing that came to my mind reset the SMC from a cold start

    You can also look a UltraFan it will do what you are trying to do with SMC FC, app is also written by a forum member


    If the temp sensor dies on a Mac the fans run at 100% as they are not sped up more held down to put is simplistically or not
  8. canhaz macrumors regular

    Jan 17, 2012
    Great, I pulled a line from there. Didn't realise I could R/W the SMC directly.

    This allows me to set maximums where smcFanControl won't allow.

    What a lifesaver so far. However, I've noticed even under the slightest bit of heat 70deg+, something weird starts happening and the machine gets 'sluggish'. It appears some form of throttling is taking place.
  9. Yaqdhan macrumors member

    Jan 8, 2012
    Muscat, OMAN
  10. canhaz macrumors regular

    Jan 17, 2012
    Ta already done that. Setting MAX RPM figures for L1 and L0 fans helps the situation. However once the CPU's get above about 75 degrees, IntelSpeedstep or something else kicks in and makes everything slow and 'jerky'.

Share This Page