This happens from both the read more.
Garage door opener starts then reverses.
The photo eyes send an infrared beam across the bottom of your garage door opening if that beam is broken the door will reverse.
When the opener reverses the screw turns the opposite way and the nut travels back.
Photo eyes or safety sensors are mounted to the track on either side of the garage door about 6 inches up from the ground.
I have a garage door opener stanley d1000 a07 date 98523 i hit the wall button or remote button and it hums starts to move then stops and reverses itself then stops.
Reverses on its own.
The 2 nd cause is the closing force could be set too light and the normal tension of the closed position exceeds what the door believes to be allowable tension.
However if the door travels all the way closed and then reverses look to the 2 nd 3 rd possible causes.
When the opener is activated the screw rotates causing the nut to move until it reaches the switch.
It goes partway down reverses direction and goes back up again.
This is almost always the result of a dirty.
If the garage door only travels down an inch or so before reversing something is probably blocking the beam between the two safety sensors at the bottom of the rails or the sensors aren t aligned.