The fact that it makes noise is a sign that its still working. First of all, disassemble the machine carefully (make sure you use ESD Mart and / gloves to handle the inside components). Take out the Motherboard and locate the fan. Unmount the fan by unscrewing in from the main board and don't forget to unplug the power connector running from the fan to the main board. Clean the fan with a light brush, you can use a blower as well to remove any dust trapped in the fan. Use machine oil or lubricant to lubricate the fan (Just a small drop will work). Make sure no excess oil lingers on the surface of the fan. Reassemble everything back together carefully and start the machine. If the noise continue, find a compatible fan and replace it. Thanks.