· by Michael Blair, Nashville's Garage Door
A garage door that starts down then reverses, or refuses to move at all, is nearly always the safety reversing sensors. They are required on every opener made since the early nineties and they are easily knocked out of alignment.
The photo eyes
Two small sensors face each other about six inches off the floor. If the beam between them is broken or misaligned, the opener refuses to close as a safety measure.
Look at the indicator lights. One steady and one blinking usually means misalignment; both out means no power to them. A cobweb, a leaf or a bin in the beam is enough.
Working through it
Wipe both lenses. Check nothing is in the path. Loosen the bracket wing nut and adjust one sensor slowly until both lights are steady, then retighten.
Check the wiring back to the opener for staples driven through it, which is a common cause and looks like nothing from a distance.
- Clean both lenses
- Clear the beam path including bins and cords
- Realign until both indicator lights are steady
- Check the wire run for staple damage
- Test with the wall button, not just the remote
Travel and force settings
If the sensors are fine, the down-limit setting may be wrong — the opener thinks the floor is lower than it is, hits it, senses resistance and reverses.
Force settings can also drift. Both are adjustable on the opener, but increasing force to overcome a problem defeats a safety system and should not be a first move.
When to stop
If the door is heavy to lift by hand with the opener disconnected, or if it will not stay put halfway, the springs are the issue rather than the opener.
Torsion springs store an enormous amount of energy and are genuinely dangerous to adjust without the right tools and experience. That is the point to call someone.