If your door starts down and reverses, and the opener light blinks once, the problem is almost never the opener. It’s the pair of photo-eye sensors near the floor — and this is the single most common service call we run that a homeowner could have fixed in ten minutes.
Unplug the opener before touching any wiring, and never place any part of yourself under a door that is partly open. This repair involves the sensors only — it does not require you to touch springs, cables or the opener’s internals.
Every opener built since 1993 has a pair of photo-eye sensors mounted four to six inches off the floor on each track. One sends an infrared beam, the other receives it. Break that beam and the door refuses to close — which is exactly what you want when a child or a bicycle is in the way, and exactly what’s infuriating when nothing is there at all.
Four things break the beam without anything being in the doorway: the sensor got bumped out of alignment, the lens is dirty, direct sunlight is washing out the receiver, or a wire has worked loose at the terminal. The first three are what this guide covers, and they account for most of what we find on arrival.
Look at both sensors. The sender shows a solid amber light; the receiver shows green. If the receiver’s light is off, flickering or blinking, you’ve confirmed the diagnosis. Note which one is misbehaving — that’s the one to work on.
Move anything stored near the tracks — a trash bin, a bike wheel, a stack of boxes will do it, and so will a cobweb hanging across the beam. Wipe both lenses with a dry cloth. Don’t use glass cleaner or any solvent; it clouds the plastic permanently and you’ll be replacing the sensor instead.
Back off the wing nut on the blinking sensor’s bracket just enough that it pivots with light hand pressure. Aim it straight across at its partner, moving in small increments. Watch the light: when the green LED goes solid and stays solid, you’ve found alignment. Hold it there and tighten without letting the sensor rotate.
If your door faces west and this only happens in the late afternoon, direct sun is saturating the receiver — shade it with your hand to confirm. Below 40°F, false reversals are common even with the sensors perfectly aligned.
Close the door with the wall button and watch it travel all the way down. Then run the safety test: with the door open, press close and pass a broom handle through the beam. The door must reverse immediately. If it doesn’t, stop using the opener and call us — that’s a genuine safety fault.
If the sensors are clean, aimed and steady and the door still won’t close, the fault is elsewhere. Use this to tell what you’re looking at — and whether it’s yours to fix.
