Garage door openers have safety sensors that prevent the door from closing if there is an obstruction in the path of travel. The sensors will stop the door and reverse direction. If the door starts to close but reverses direction before it moves five feet, you will need to adjust what is known as the down force. A door that closes to the floor and then reverses requires adjustment to what is referred to as the down travel limit. All adjustments are made in small increments to prevent over adjusting the limits.
Adjust Down Force
Position a stepladder under the garage door opener motor head so that you can reach the back and side of the opener motor head. Take the remote control with you and find the force adjustment limit screws on the back or side of the opener motor head. There is an up force and down force screw. Both are white and in line with the limit adjustment push button or screws.
Turn the down force adjustment screw 1/4 turn counterclockwise with a flat-head screwdriver. This will decrease the sensitivity of the down force limit.
Press the push button on the remote control to open the garage door if the door is not already open. Press the button again to close the garage door. Continue making fine adjustments to the down force limit screw as necessary.
Adjust Down Limit
If your door closes all the way but comes back up once it hits the ground, locate the down travel limit screw on the opener motor head. Some newer models of garage door openers use a push button while older models use a screw that is flush with the side or back of the motor head.
Turn the down limit screw 1/4 turn counterclockwise with a flat-head screwdriver if your opener uses the screw type adjustment. If your unit uses the push button, find the "Set Limit" buttons beside the force adjustment screws. Tap the "Set Limit" button that has the arrow pointing to the ceiling. This will move the door in small increments.
Push the button on the remote control to open the door fully. Push the button again to close the door. The door should seal to the floor without reversing. Continue making these small adjustments as necessary.