LFC#104 - MacBook Air Fan on High-Speed

LFC#104 – MacBook Air Fan on High-Speed

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A sensor fault is keeping the fan on this MacBook Air running at max speed.

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Counterwise –

hello interwebs welcome to let's fix computers we're looking at a map of air today that has an angry sounding fan and we like that you can hear the fan is running on a high speed at the moment so we need to find out what's going on with that so a fan running on high speed on a computer is going to be a couple of things it's going to be either that the computer is overheating or there is a problem with the computer now and on in the case of a MacBook nine times out of 10 if your family's running on maximum speed at idle so I on the login screen then it is probably going to be a sensor issue if there any of the sensors in your MacBook are not reporting their room their settings properly then the map will automatically kick the fans on to high speed just in case another symptom is also the computer will probably be running very slowly although the amount of slowdown varies depending on the make the year and the type of map so what we're going to do we're going to start this thing up off of Apple service diagnostics and Apple tell us which sensor has failed so let's plug that in and we're going to go ahead and turn this off and boot from my a SD disk all right so apologies for the lack of video capture but I don't have a I don't have a thunderbolt to HDMI cable in the shop at the moment so we're gonna have to do this the crap way so let me see 3 X 1 5 6 for this because this is a 2014 ok right so we're going to deselect all the tests except the sensors because you know it's going to be a sensor on this so status and on arrow we're going to continue if give as I failed sensor so what's that as th 1h thin stack there's another error that's the same one th one each thin stack okay so th one edge fin stack I'm just going to quickly make a note of that before I forget okay so let's turn this thing off and let's have a look at that sensor and do a visual inspection on it now I'm very foolishly dusted this laptop out as soon as it came in thinking I was probably overheating or something like that now there was actually almost no dust in the laptop however there were a couple of other sketchy looking marks so I think that there is probably going to be well yeah basically I've rubbed away all of the clues which is a really silly thing to do but thankfully because we have an actual diagnostic sensor that we can look up it should be quite easy to find out where the problem area is so not to worry all right so as you can see this thing is actually really clean on the inside let's bring the camera a little bit closer however when I was working on it I did see that there were some there were a couple of signs of some possible like water damage around masks group then there was some stuff around there and there was also some stuff around here so those are the areas that I'm expecting to see stuff you can also see a little bit of rust on those screws which just shows where there's been a little bit of water ingress into this laptop at some point very very mild but there's been something so let's get a schematic out of this and find out where th one H is okay so here's a schematic for the eight two oh three four three seven let's start searching so firstly what about th one H is it gonna be that simple no it's not okay what about fins stack then stack all one word yes what is that thin stack sends alerts low okay that's that's something along those lines if our 52:10 let's look up our 52:10 and just quickly check where that is because that might get us into the rough region that we need to be in however these are all pull-up resistors so they might not be in the right place okay and so that is next to the youth 5000 which is the SMC unless I'm mistaken that's not going to be it because that's not next to that's not next to that's not in the right place for our thermal sensor this thermal sensor is going to be near the heat sinks somewhere so this isn't it these are just all pull-up resistors for other senses however we could follow that back actually so let's see where that goes to so well fin status alert l okay that goes back to Jay 9500 so this is the connector that goes over to the DCN board so that certainly implies that this thermal sensor is on the DCN board which just as a reminder that is this fellow here we're talking about so that's Jay 9500 there and we're moving across to there on the DCN board and the sensor is going to be around this area here next to the fin stack so in all probability a replacement DCM board is going to fix this so let's grab another DC and board and see if that fixes it naturally a lot of scum shown up on the back of this dcn board wonder what the back of this gonna look like now I can't remember I think we can get this DC and board out without removing the logic board which is great because I'm lazy I just need to get the fan out the way okay so there's our DC em board backside it is completely clean however we've got some skank around there and a little bit of patchy area around there okay so here is another known good DC and board from my tester MacBook Air which i think is also 2014 so let's plug this bad boy in and see if it works okay we'll reroute all these wires and stuff when we know that the problem is fixed get that plugged in and that lot is all unnecessary we don't need that running or that lot to work okay right let's bring up ASD again and see if our problem has disappeared okay rice and we're gonna remove all all night is already that I'm not hearing a very noisy fan sensor continue on era go CH 1 H fan is working sensor is working even all right that's it so it's this fella causing our problem annoyingly the DCN board is not on the schematics or the board views so we can't find the sensor itself however because we've got some visible corrosion there I might just take a closer look at that and try cleaning it out see if I can save myself from having to you were buying another dcn board there's the other test for th one H once again that one is passed yeah we're all good okay so we've got a short spin on this now so let's turn that off again okay so firstly we're gonna make a mental note on what visible damage we've got here so we've got this area here and this area here that's all we have to go on at the moment I think it's going to be this area here because we've got what looks like some crappy looking test points and on the other side of the board on this position we've got these two fellas here in here now that I would guess that looks like a thermal sensor to me they're about that makes logical sense and if that's got a veer going to the other side of the board it's got to go through that which is all messed up so let's just try alcohol in all of this first and see if we get lucky okay I'm not gonna touch anything so that's already clean now having brushed away the corrosion there it still looks kind of darkened let's just see if I can get you guys a super close-up of that there we go so as you can see those points when you look at those silver dots there those look fine however those do not look fine likewise that one looks a bit ropey as well now these are probably beers where run where the copper path the trace goes through the circuit board to the other side onto those fellows that is probably our thermal sensor the little six legged ship and that's a tiny little capacitor next to it I'd imagine that's my guess however as I said because we don't have a schematic aboard view for this section of the laptop we don't actually know so if that fellas burnt out there's nothing we can do about it I mean I could run wires around this thing but I had to helps it's really worth it let's find out how much a replacement board is just to find out if I'm wasting my time or not okay so 2014 MacBook Air DC DC board all right so we got 17 quid can we get better than that new in the UK by now 1650 yeah it's it's not worth arguing over that so yeah new DC and bored and we're done alright now this laptop is in on priority service so this faulty one I'll hang on to this and I'll give the customer than my working one and I'll buying the replacement so all's we got to do now is just tidy up with the laptop and we've finished so let's quickly finish reassembling this thing again my good man here oh you asshole shoot over hat okay look at this tell me what's wrong with this picture those two connectors are different this DCM board is a very slightly different revision goddamnit and it's so close it makes you beg the question why are they different in the first place do we have microphones on the other side of this laptop no so basically without back connector there's no microphones damn it alright so what I'll have to do is call the customer and say if you want it back really super fast then you're gonna have to live without microphones or if you can wait a couple of days we can get the correct DCM board and you will have microphones again fine okay let's just put these screws in so the laptop is in one piece and then at least we can finish the video there we go right so if we had the correct DCM board we would now be finished I also just noticed on this DCM board we have the the webcam connector whereas on the original one we don't have the webcam connector that's actually connecting back under here there so obviously that's a nice sight HD camera versus this one which is obviously from the non HD eyesight so this is probably this is still a maxine21 this is probably fourth gen and I think this laptop is fifth gen MacBook yeah fifth or sixth so yeah but a couple of subtle differences so that's why they're different fine okay that would be the assembled map top we're gonna have to go away and get the correct decian board because there's too many differences here however the laptop itself is fixed so that's good enough for me so where you get the idea we'll replace that with correct one off camera and I'll see you all next time good bye for now so I just spoke to the client on the phone to get a green light on the past cost and they said that apparently their daughter uses the laptop in the bathroom so they're in the bath and they have a laptop sitting on a stool next to the bar so obviously the steaming room is what has caused the corrosion in the laptop which explains why there was no obvious signs of liquid damage just a very light corrosion in a couple of key locations so that solves the mystery of why it was broken in the first place

17 Replies to “LFC#104 – MacBook Air Fan on High-Speed”

  1. M

    Fantastic. Great quality video and well explained / shown. Thank you kindly for the upload.

    I have an early-2015 Macbook Air. Will the DC inboard still be in the same location? I am going to attempt this masterpiece you just performed…

    The end of the video, explaining using it in the bathroom…. yea…. that's probably why mine went too. Haa. Thanks again!

  2. Farrel Akbar

    i want to ask something if i gaming every day on my macbook air is it posible to melt the component

    btw i bought the Air (13-inch, 2017) please answer it

    i own the macbook air around 1 year

  3. Lilly Wyatt

    Hi, my three month old Macbook Air suddenly started running very slowly with loud fan noises. I tried resetting the SMC and the laptop wouldn't restart. I eventually managed to reset the SMC again and computer turned on but again ran extremely slowly with the overactive fan. I took it into a Mac store and after examining it and saying there was a fault with the logic board, which they'd fix under warranty, they rang over two weeks later and said they'd found corrosion on the flex cable caused by liquid damage. This is insane as I've not used the machine much and definitely haven't had any spills. It's not been out of the house more than once and it's been in a case most of the time. They're now quoting £668 for a new top case, keyboard, trackpad, logic board and flex cable), plus labour. They won't send me any reports, so it seems a bit dodgy, but my technical know-how is very limited! Do you have any advice and does it sound like I need all these parts?

  4. Paul Curran

    U seem to know what u are doing, at least more than me anyway, I have a long running problem that maybe I could answer for me, it's worth a try anyway…..

    I'm using a macbook pro late 2011 and have a similar hard working fan issue, the error code is 4SNS/1/C0000008: Ts0P–124

    I've replaced a few things, directed by fourms to do so…… I've replaced the fan heat sinc and the lead that connects the hard drive to the motherboard, both with no avail….. because of this issue I have no wifi and cannot update anything, it's still running with OS X Lion

    Could u possibly give me some things to try that don't cost me a bundle……thanks

  5. Mohamed Elabshihy

    Thanks for sharing this good information, can u please tell me how to get that program u used to check the sensors ?

  6. Mohammad Naseer Batla

    Can a faulty ambient sensor not only cause fans to be at full speed but also randomly turn the MacBook to sleep?

  7. Cristián Loyola

    Hi, thank you for sharing your video. I have the same problem that you show in your video. I wanted to ask if in the circuit that I replaced is the fan temperature controller and if the equipment behaved slowly. Thank you very much for sharing your knowledge.

  8. Claude Champagne

    Hi, I have a MacBook Air bought in 2017. The fan runs loud for no reason from time to time. No high CPU usage. I checked with the Macs Fan Control app. Temperature is OK. I tried to reset the PRAM and the SMC. No luck. The only thing that will stop the fan is when I change the settings for the sensors in Macs Fan Control. The fan burst for 2 seconds and goes to normal after. I've ran the Apple Hardware Tests in the Recovery. No test failed. I really don't know what to do more. I went to the Apple Store, when my computer was still on warranty. They said they changed the fan and the motherboard. But it hasn't changed anything. Not sure they really replaced anything… Have to believe them. 🙂

  9. Juan Alonso Urra Peralta

    How can i get the program? I want test my macbook air, its have the same problem fan over speed and the system very slow. Thanks for your video

  10. Nikhil Kaul

    Hey I have a MacBook Pro 2012 mid and it says my ambient sensor has a problem …can it be solved by changing the dc board
    Cuz Apple store is asking me $500 to change the motherboard in India

    Pls help me if there’s any cost efficient way to fix this issue

  11. Janeks Raphael

    Very good videos, i like the way you're explaining things, easy to understand for non-tech person, may i ask you where did you get diagnostic software? I'm not asking for download link, just could you point me some direction???
    Thank you

  12. VisualLife

    My MacBook is doing the same thing… how does the fan sensor problem make the Mac run very slowly. I got a program that lowered the fan speed but it didn’t change the computers performance.

  13. Stockholms Oskar

    From Mid 2013 the Air has it's iSight connector on the main board and no longer on the DC IN board like the -10,-11 and -12 version.

  14. Tom de Boer

    Thanks for your video's, very educational and well-explained :). Also, where did you get the diagnostic software and schematics from?

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