Lay down several sheets of newspaper on the ground below the vent to catch any dirt that you sweep out.
Detach the fireplace vent from the outside of your house with a screw driver.
Clean the fireplace vent itself with a dry cleaning brush. Set it to the side.
Use a fireplace cleaning brush to scrub the pipe that leads into the fireplace. Be careful not to damage the pipe while cleaning. Sweep as much of the dirt and debris out of pipe and onto the newspaper.
Use the hose attachment on your vacuum to remove any dirt or debris that you may have missed with the brush.
Shine the flashlight into the pipe to inspect for any remaining dirt and also for cracks and damage to the pipe. If you notice any damage, contact a professional fireplace repair service to fix and/or replace it.
Place the fireplace vent cover back onto the pipe and screw it back in place.
Carefully fold up the newspaper to avoid spilling any dirt and throw it away.
Go inside and use the vacuum to clean out any dirt or debris that may have fallen into the actual fireplace when you were cleaning.