Guardian opener motor runs but door closes very hard, slamming into the floor.

Safety first: Keep clear of the door while adjusting. Excessive force can damage the door or cause injury.

• Adjust down travel: Reduce the down travel limit on the Guardian opener so the door just contacts the floor and stops.
• Reduce down force: Turn the down force adjustment to a lower setting per the manual.
• Check bottom seal: Ensure the bottom seal is not so thick that it requires excessive compression to seal.
• Test safety reversal: Place a 2x4 flat under the door and close it. The door must reverse upon contact. If not, reduce force further.