Locate your circuit breaker and turn off the power circuit to the room you will be installing the ceiling fan in. There may be more than one for this room, so turn all possible switches to the off position.
Disconnect the existing light fixture.
Disconnect the wiring to the light fixture. Remove the old fixture.
Look to see if there is an existing metal bracket or work box from the old light. If there is, it may be suitable for you to install your fan with. It must be a metal bracket, not plastic. If you are going to use the existing work box, move to step seven.
Install a 2-by-4-foot block of wood between the joists and over the spot where you are installing the ceiling fan using screws and a screw gun. You will need to go into your attic to access this area. If you do not have access to the area, install an expandable metal support beam from below. You can find this at home improvement stores. The beam will serve as support for the mounting bracket. If you have the part, you can install a metal support beam by feeding it up through the hole where you will be installing the ceiling fan.
Mount the metal work box to the support beam from below.
Assemble the fan according to the manufacturer's instructions. You will want to have an extended drop pole for your cathedral ceiling when assembling the fan. This will allow the fan to hang lower and not hit the ceiling. There should be at least 18 inches of clearance between the blades and the next closest horizontal measurement to the ceiling.
Take the mounting bracket to the ceiling work box. There are fans that will have a J-shaped hook to hang from the ceiling while working. Others might have a hanging frame to hold up the fan while you are working.
Follow the diagram in your ceiling fan kit to hook up the wiring to the ceiling using the wire nuts. You will most likely connect the wires according to color, ensuring that the ground wires are connected.
Install the canopy to the ceiling according to the manufacturer's instructions.
Assemble the fan blades and lighting.
Turn on your breaker and test your work.