How to replace a T43 fan
The ThinkPad T43 has a number of well document fan/cooling problems. Replacement fans are available on eBay and elsewhere for reasonable prices and moderately easy to install.
Selecting the Correct Replacement Part
The first challenge is ordering the correct replacement part. The T-series has a bunch of fan assemblies and 3rd party sites don't always do a great job of labeling what they are selling. The Lenovo Parts Lists should give you a good idea of what you are looking to buy. Or open the system and look at the sticker on the upper left edge of the fan unit for a model number.
Opening the Case
Use the service manuals (linked at the bottom of the page) for instructions on how to take apart the system. In short remove (and keep careful track of) all the screws on the bottom of the system numbered 1, 2, 3 or 4. To do so you'll need to scrape the flexible plastic covers off the screws under the front edge of the system. A flat head screwdriver works well for this. Be sure to note that not all screws from holes with the same number are identical (ex: one of the screws from a #4 hole is unlike the others). Once the screws are out open the laptop and remove the palm rest and keyboard completely.
Swapping the Fan Units
The fan unit should now be obvious. Compare your replacement to the original to insure a proper match.
Getting the unit out can be very difficult, use to the service manuals for additional help. You should see three small screws sitting in complex spring loaded brass setting. These screws can strip easily, be very careful when you remove them. To do so without stripping the screws you'll need to find a way to press down on the inner edge of the spring loaded setting (part that sticks out towards you the furthest). This should take the tension off the threads of the screws making removal possible. If you do not hold down this lip the threads will be under tension and head will almost certainly strip. Make sure you have a very small screwdriver for this part - only slightly larger than an eyeglass repair screwdriver.
I have found two ways to keep pressure on the edge of these settings. The first is drilling a hole in a nickle, just large enough to fit your screw driver through but smaller than the flange. This gives you something big enough to press on while removing the screw (a second person is helpful). The other option is using a pair of diagonal cutters example to vertically snip the protruding flange in 4 places, every 90 degrees around the lip. Then flare the edges out slightly making a larger surface to press down on. Obviously this method is quite risky.
Once you get the three screws out unplug the fan from the board and gently remove it. The service manual talks about using a screw driver to pry it out. I have found gentle wiggling is enough to get it out.
Make sure your new fan unit has thermal grease on it right over the processor. A matrix of dots is a good way to make sure you cover the whole CPU area but extra isn't squishing out all over the place.
Put the screws back in, again holding the spring loaded flange down while tightening the screws (the coin method comes in handy here). Put the whole case back together again.
Test Your New Fan
You can test your new fan by pressing the Access IBM button on start up and going into the hardware diagnostics mode.
Service manuals for the T43 Hardware Maintenance Manual (July 2005) - ThinkPad T43/p (2668, 2669, 2678, 2679, 2686, 2687) See page 107 for Fan assembly removal instructions
Hardware Maintenance Manual (July 2005) - ThinkPad T43 (1871, 1872, 1873, 1874, 1875, 1876) See page 106 for Fan assembly removal instructions Other helpful links Replacement with Photos