To remove the system fan. Loosen the 8 screws on the base cover. Pry the cover away from the recess points near the hinges. And remove it. Identify the fan. Disconnect the cables. Remove the two screws. Lift the fan out of the system.
To reinstall the fan, place it back in the system. Install the 2 screws. Reconnect the cables. Install the base cover into place. Tighten the eight captive screws that secured the base cover.