While most ceiling fans come pre-packaged with a down rod, it doesn't necessarily mean that the down rod is sized right for your room. In some cases, proper installation of the ceiling fan may demand a longer or shorter down rod. The problem arises when the ceiling fan is already installed and you're faced with having to change the down rod so your ceiling fan works as well as it's supposed to.
Set up the ladder so that the ceiling fan is slightly in front of it. Have someone on the ground to help you while you are working on the ladder.
Turn off the circuit breaker that powers the ceiling fan.
Remove the screws that secure the ceiling fan's canopy to the mounting bracket and let the canopy slide down the down rod.
Test the wires for voltage using a touch-type voltage tester. If it reads voltage in the fan, check to make sure the correct breaker is turned off.
Disconnect the wires by removing the wire connectors and separating the wires. Lift the ceiling fan to unseat it. (Be careful--the fan can be heavy and somewhat cumbersome with the blades still attached.) Hand the fan to your assistant on the ground and come down the ladder.
Look at the base of the down rod for a pin and clip system that holds the down rod in place. There are also two or three screws tightened against the rod. Loosen the screws, remove the clip using needle-nose pliers and pull the pin out. Slide the down rod out.
Push the ball joint down the down rod so you can remove the small metal bar at the top of the rod. Slide the ball joint off of the rod.
Take the new rod and slide the ball joint onto it. Insert the metal rod and pull the ball joint up so the rod sits snug in its slot.
Fish the ceiling fan's wires through the bottom of the new down rod. Once the down rod is in place, insert the pin and secure it with the clip. Tighten down the screws that surround the base of the down rod.
Re-install the ceiling fan as it was installed previously.