First, make sure your garage door opener has a reversing feature. It's easy to know... from the inside of the garage with the door closed you should notice two sensor "eyes" located about 6 inches above the ground on each side of the door jamb. (note: these usually have a visable red or green light) Those sensors detect objects under the door and MUST be there and MUST be in working order.
Any garage door opener without this feature needs to be replaced. Garage door openers manufactured after January 1, 1993 are required by federal law to have advanced safety features which comply with the latest U.I. 325 standards.
Here's how to test the Reversal feature. (note - it's a good idea to do this every month or so).
- With the door fully open, place a full roll of paper towels on the floor in the center of the door.
- Push the remote control or wall button to close the door. The door must reverse when it strikes the roll of paper towels. (Note that the bottom part of 'one piece doors' must be rigid so that the door will not close without reversing).
- If the door does not reverse, have a certified technician adjust, repair or replace the sensors, the opener or the door.