To Replace the Fan. Simply pull the fan from the rubber mounts starting at one corner and gently pull the corner up until the mount releases. When reinstalling the fan, ensure the airflow is blowing in the desired direction. There is a arrow on the side of the fan that indicates the direction of the airflow.
Polarity. This fan is polarity protected so if polarity is reversed, the fan simply will not operate. Just reverse polarity ensuring that Tip aligns with + on the ends of the connectors.