NWA-PCUG Newsletter Article, December 2011
Your Computer's Health, Part 5 - Temporary Fix for a Bad Fan
By Bob Woods,
UCHUG (Under the Computer Hood UG) Webmaster, CA
May 2011 issue, The Drive Light
http://www.uchug.org webmasters (at) uchug.org (click to email author)

Have you ever turned on your PC and had a rumbling or squealing sound come from somewhere inside the case? Everything will appear to be working fine, but the PC sounds horrible. What you are hearing will most likely turn out to be a fan whose bearings have worn out. The offending fan can be one of the many fans found on today’s PC’s. Typical locations are mounted to the case, mounted inside or outside of the power supply, part of the CPU cooler, or mounted on a graphics card. Most PC fans have 12 volt DC motors and consisting of a housing supporting an enclosed motor with a multi bladed fan shaped like a cup with fins. With the exception of some graphics card fans, most fans are replaceable.

Once you have located the noisy fan there is a temporary fix. First, make note of which side of the fan is facing you. That will ensure that when you reinstall the fan the correct side will be up for moving air in the proper direction. Then remove the fan. Most fans will have a sticker on the side of the fan that has the motor supports. Carefully peel the sticker back to expose the shaft and bearing for the motors armature which is attached to the fan blade cup. Do not completely remove the sticker as you will want to stick it back down to cover the bearing back up. A drop or two of a light oil (I use 3 in one) will often buy you some fan life. Do not get too carried away with the oil as too much will leak back out and get thrown around to nearby parts creating a dust magnet. Make sure to cover the bearing back up with the sticker to keep dust out and help contain the oil. Unless the bearing is completely shot the fan should go back into service long enough to allow you to get a new replacement fan. Most replacement fans cost less than the shipping cost and suppliers can be found on line by doing a Google search. Often the small fans for CPU coolers and graphics cards will be measured in millimeters. Just measure the fan in inches and Google inch to mm conversion. The fan size in mm will end up being an even number of mm in 10’s. A close to 2 inch square fan converts to 50.8 mm which is actuality, a 50 mm fan. A search on Google or Amazon will help find the fan you need and will usually have the required connector. But, what if you have a replacement fan that did not come with a connector or the only one you can get doesn’t have the same connector? Take a quick trip to any store that carries electrical supplies and get some insulated butt splices.

Often you can find a kit with different sizes of butt splices with the crimp tool in the package. You may also already have a set of wire strippers that have the jaws used for insulated crimping. Cut the wires from the old fan about 2 inches from the connector. Strip about ¼ inch of the insulation from the wires for the old and new fan and use a butt splice for each wire to connect the fan connector. Make sure you follow the wire color code so the fan spins in the correct direction when mounted. For colors, usually blue and black are the colors you would see for the negative lead and red or white for the positive lead. Another helpful hint is there is usually an arrow showing direction of air flow stamped into the fan housing. Use this as a further guide on mounting the new fan so the air movement will be the same as the original fan. If you have a third lead it will often be yellow in color and is connected to a sensor inside the fan motor. The sensor will allow the fan RPM to be monitored. Most late model CPU coolers have a fan with this sensor which is monitored by the motherboard BIOS. If the fan RPM falls below a preset limit the BIOS will give you a status warning during boot up and can even prevent the motherboard from completing the boot up sequence. In the event you cannot locate a replacement fan with the sensor most BIOS will allow you to disable this feature.

Remember, a fan that has bearing noise is usually close to its end of life. Using a drop of oil is a stop gap measure to allow you time to locate a replacement. But this grace period can be a life saver, especially when you are depending on your PC to complete an important task.

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