Garage door sensor not working? Here is what it means

Since 1993 every opener has shipped with two small eyes near the floor, one on each side of the opening. One sends a beam, the other watches for it, and the moment the beam breaks during a close the door reverses. That reflex is what keeps a door off a child or a car bumper, so it's tuned to be jumpy.

A door that won't close with a flashing light is therefore an opener doing its job on bad information, not a broken opener. The work is finding out why the eyes can't see each other, and it is a short visit.

The order the faults come in, which is the order the technician checks them.

1. Something in the beamA trash can, a bike wheel, a cobweb, a leaf. Anything in the six inches above the floor between the two eyes trips them, and the door will not close until it is gone.
2. A dull lensSalt air off the water rusts cables leaves a film on the lenses, and a dull lens loses the beam at dusk first.
3. A bent bracketEach eye sits in a bracket that bends easily. A bumper, a bin or a bike knocks one out of line, and an eye that keeps drifting out of line every few weeks is a bracket that never holds, not an eye that needs setting a fourth time.
4. Sun in the receiverLate afternoon sun straight into the receiving eye blinds it. A door that only misbehaves at one time of day is nearly always this.
5. A damaged wireA staple through the thin sensor wire, a splice that has come apart, or the terminals at the opener working loose. Both eyes dark is usually a wire.

Steady LEDs and a clear beam but the door still reverses means the opener has a different complaint. Reversing right at the floor is the down-limit set a touch too far. Reversing part-way, with a door that is heavy, is a spring that has lost tension tripping the force setting. The first is adjusted on the visit; stop using the opener until the second is fixed.

Cold-weather-only reversing is the same thing: Salt air, nor'easters and hard winter freezes, the door stiffens, the force setting trips.

Eyes do die: water in the lens, a mower strike, a board that gives up. A matched pair for Chamberlain, LiftMaster or Genie is stock on the truck and takes about twenty minutes to install and align. They don't cross brands or generations; the label on the motor unit tells us which pair.

Damaged wiring gets rerun with clips instead of staples, which is why it doesn't come back.

The brackets matter as much as the eyes. Both sensors should sit at the same height, a few inches off the floor, and a bent bracket keeps drifting however often it's reset. If the same eye needs attention every few weeks, the bracket is the fault, and it's replaced on the visit.

Beam, lenses, alignment, wiring, in that order. A cloudy or dead eye gets a new pair. Before leaving, the technician disconnects the opener and lifts the door by hand, because reversing doors often have a spring problem hiding behind the sensor one. Free estimate across Brooklyn, Queens and Long Island.

Short visit, usually. The long ones are the doors that were out of balance for a year.

The opener is broken. The opener is fine; it's refusing to close on what looks like an obstruction. Fix what the sensors see and the opener behaves.

Just bypass the sensors. Don't. A door without working sensors is the door that comes down on something. Call, and the eyes are working the same day.

New sensors mean a new opener. No. Sensors are a matched pair that plugs into the existing unit. Twenty minutes.

Around Brooklyn, Queens and Long Island, one call gets you a two-hour slot and a heads-up call before the technician sets off. Nobody on a phone judges a door they can't see.

Free estimate, across Brooklyn, Queens and Long Island.