Installing a Ceiling Fan Using Existing Wiring

Answer:  You will have to remove the old ceiling light electrical box as it is not approved for ceiling fan support.  Shut off the circuit breaker for this particular lighting circuit.  Start the removal process by disconnecting and separating the wires and identifying them.  This will help when you put them back together. 

Loosen the wire clamp or connector.  Remove the center screw(s) that holds the box to the support brace and carefully pull the box down while removing the wire from the box.  Do not cut or damage the wires. 

Removing the old ceiling box support bracket that is up inside the ceiling can be difficult.  I usually just use my 24" bolt cutter's to cut it in half.  Then I swing the cut pieces forth and back to see if they loosen from the ceiling.  Most of the time they are nailed in and the longer the nail, the more difficulty there is in removing the bracket. 

I also have some short pry bars for just such an occasion.  I can get a pry bar up in the ceiling and reach over and get it behind the nailed-in bracket and give it a few tugs to get it loose enough for removal.  Persistence is the key.  If you get frustrated with the old box removal, take a short break and then get right back at it.