Problem: Bad fan

Cost: $15 to $25
Time: 1 hour
Materials: Screwdriver, compressed air, replacement fan

A noisy or broken cooling fan is not only annoying but doesn't bring enough cooling air into the case, potentially causing the notebook to overheat and damage the electronics inside. Fortunately, it's not a hard repair to make. In fact, if you're lucky you may not need to replace the fan at all.

My Toshiba Satellite Pro 6100 has a single cooling fan, although many systems, particularly larger gaming and entertainment systems, have two or more fans to bring in cool air for the processor, graphics hardware and hard drive. More often than not, the fans get clogged with dust, debris and dirt, which can make them noisy and lower their efficiency. If your system is making a whirring or grinding noise or is overheating, this repair is for you.

Blow compressed air into the slotted grilles.

Before you do anything else, find the place(s) where fresh air comes in and hot air escapes -- usually one or more slotted grilles on the side or bottom of the system. There could be two or three vents, so don't give up easily. Insert the plastic straw from a can of compressed air into each vent and blow out all the dust that you can; you might want to put on a dust mask or have a vacuum cleaner running because there can be a disgusting amount of dust.

If this doesn't fix things, it's time to dig in and open the case. There are generally about a dozen screws on the bottom of the case that you'll need to remove to open the case, but it varies widely depending on the notebook -- for instance, some models require you to remove the keyboard to get inside. If it's not immediately obvious, check your manual or do some online research to find out how your case opens.

After carefully opening the case, find the fan and blow away any additional dust or detritus.

Open the case and remove any dust or detritus that impedes the fan.

While you're there, take a good look for anything stuck in the fan's blades that might be impeding it. Twirl the blade with your finger, and if it makes noise or doesn't spin freely -- as was the case with my Toshiba -- it needs to be replaced.

Before going further, write down the model number of the fan and go online to find a replacement fan. Use your favorite search engine and type in the model number and "cooling fan." Chances are that even for a five- or six-year-old computer, there will be fans available from several spare parts stores, such as ComputerTopRepair.com. The replacement should cost anywhere from $5 to $20.

Carefully remove the old fan.

Once you have the new fan in hand and are sure it's the right one, you can take out the old fan. First, unplug the fan's power connector. Each system is different, but you'll probably need to unscrew a frame that holds the fan in place, and then undo some screws holding the fan to the frame.

Now you can gently remove the fan. It might take a little finesse to work the fan loose because it's generally a tight fit in there. Many notebook fans are connected to the heat pipe, a thin silver- or copper-colored tube that draws heat off of the processor or graphics chip. The heat pipe usually snaps or screws into the fan assembly. Try not to bend the heat pipe when you're removing the fan because that will reduce its efficiency at cooling the processor.

With the new fan ready to go, slip it in and carefully screw everything back in place. Before you screw the bottom of the case back on, plug in the power connector and fire the machine up. Don't worry if it doesn't start right away because the fan may turn on only after the system heats up. Once you've verified that it's working, close the machine up and get to work.