Replacing just the fan and motor is fairly straight forward but the most important thing is to get the right parts before you begin. Make sure your replacements have the same model numbers, volts, amps, etc. as the fan you're taking out. Another thing is to have a manual for that unit so if there's any questions you have a good resource to fall back on. Now for the easy part: WITH THE POWER SHUT OFF!!!!!!!!!! trace the wire/wires to where they connect to the power supply and unplug them or cut and strip if they're hard wired to the unit-at any rate you want what you're taking out to look like what you're putting in. Now it's just a matter of loosening screws and remembering where they came from. Assemble in reverse order.