If you have a non-Unibody MacBook Pro, and it suddenly starts to make an odd grinding noise, there are a number of possible explanations. The most obvious choice, especially if the noise occurs when the computer is working very hard, is the hard drive. Hard drives fail for many reasons, and once the failure begins, requires a replacement.
However, if diagnostics show that your hard drive is fine, it may be one of the machine’s fan motors that is failing. In some ways, this can be just as serious as a hard drive failure, as excessive heat can lead to permanent damage to your computer’s internal components.
The first step is to confirm that the noise is indeed a fan motor. iStat Pro (free) is a widget that will help to diagnose the problem. Once installed, iStat Pro will allow you to see how fast your fan motors are spinning. If the noise consistently occurs when the fans are spinning faster than 2,000 RPM, especially as they approach 3,000 RPM, it is extremely likely that a fan motor is the culprit. Since iStat Pro allows you to see how fast each fan motor is running, look for one of them to be lagging behind the other in RPMs. It is completely normal for the two motors to vary by a few, or even a few dozen, RPMs. However, if one is hundreds of RPMs slower than the other, it is safe to conclude that motor is the failing one.
The next step is to go to www.PowerBookMedic.com. Once there, search for “fan,” and you will be presented with a number of options. Follow the guide to determine which is the appropriate model for your machine. Most of the options will usually be around $50.
When your new fan arrives, you will need:
- #0 Phillips screwdriver
- T6 Torx screwdriver
- Can of compressed air
The next steps will require approximately 30 minutes, much patience, and very careful execution. Keep in mind that any damage inflicted on the machine while following the next few steps will not be covered under warranty (if the machine is still new enough to be under warranty). You should also be careful to label each set of screws that you remove, to ensure that you put them back in the proper place.
Once ready, follow these steps:
1. Turn the machine off and remove the battery.
2. Remove the two Phillips screws in the battery compartment, close to the computer’s latch.
3. Remove the three Phillips screws holding the RAM door, and then remove the two T6 Torx screws on either side of the RAM bay.
4. Remove the four Phillips screws from the bottom rear section of the case.
5. Remove the 10 Phillips screws that are long the sides, and back, of the machine. Four are on either side, with two on the back.
6. With the machine standing right side up, and the lid opened, very slowly pry the top plate (containing the keyboard) up, starting at the rear of the case (near the screen). Once it starts to come loose, very gently lift it up and look underneath it. There will be a ribbon cable connecting the keyboard to the motherboard. Gently disconnect this cable from the motherboard, and remove the top plate.
7. You should be able to clearly see the two fans. Depending on which one is failing, you will have to remove different components. If the left fan is failing, there could be as many as four sets of cables/ribbons that cross the fan, or originate from it, and plug into the motherboard just to right of the fan. If the right fan is failing, you should only have to worry about the power cable originating in the fan, and plugging into the motherboard to the left of it. In either case, gently unplug the various cables and remove the 3 T6 Torx holding the fan in place.
8. With the fan out, use the can of compressed air to blow out the fan slot, as well as the rest of the computer’s components.
9. Repeat steps 1 – 7 in reverse order, installing the new fan in place of the old one, to reassemble your machine.
One the machine is reassembled, start it up and do something CPU intensive, such as watching a movie or playing a video game. You should find that your machine runs as quietly as the day you brought it home!
Obsessed with tech since the early arrival of A/UX on Apple, Sudz (SK) is responsible for the original editorial direction of AppleToolBox. He is based out of Los Angeles, CA.
Sudz specializes in covering all things macOS, having reviewed dozens of OS X and macOS developments over the years.
In a former life, Sudz worked helping Fortune 100 companies with their technology and business transformation aspirations.