Garage door sensor not working on a hot, gritty afternoon?

Bolted near the floor on each door track is a small electric eye. The pair work as a team: one sends an invisible ray across the doorway, the other waits for it. If the ray is broken while the door is lowering, the opener backs the door up at once. That rule has been built into home openers for decades, and it's the reason garage doors don't land on kids and pets anymore.

So the flashing light and the bouncing door usually mean the opener is fine and simply doesn't trust what the eyes report. The job is finding out why the ray isn't getting across, and it's rarely anything that calls for a new opener.

In roughly the order we find them:

1. Grit and grimeThe wind here carries fine grit into every garage, and it sticks to the lenses along with the film that builds up in summer heat. A grimy lens lets through less of the ray, and the catching eye gives up.
2. Clutter in the doorwayA cooler, a bag of potting soil, an RV cord coiled on the floor, a kid's bike. Anything in that knee-high band across the doorway keeps the door from going down.
3. A bracket that got bumpedThe little brackets bend when a bumper, a mower or a snow shovel catches them. A bracket bent back into place more than once never stays aimed, so it's replaced with a new one.
4. Afternoon glareWest-facing garages take the low afternoon sun straight in, and a direct shot into the catching eye blinds it. Trouble at the same hour every day is the giveaway.
5. Cooked or pinched wireHeat in a closed garage dries out the thin wire's insulation, and staples, mice and loose screw terminals do the rest. When neither dot is lit, this is usually where it ends.

If both dots stay steady and the doorway is clear, the opener is reversing for a different reason. A door that bounces the moment it reaches the floor has its down setting a bit too deep. A door that reverses halfway, and feels heavy when you lift it, has worn springs pushing the opener past its force limit.

Grit makes this worse. Mixed into the grease on rollers and hinges, it turns into a grinding paste, the door stiffens, and a force setting that was fine in spring starts tripping by fall. That's why the technician checks the door's moving parts along with the eyes.

Eyes don't last forever in a hot, dusty garage. Housings crack, lenses cloud, and a bumper eventually finds one. Matched pairs for LiftMaster, Chamberlain, Genie and the other common openers ride on the truck, and both eyes are replaced together because they're built as a set.

Bad wire is replaced along its whole run and held up with insulated clips, away from the tracks and anything that gets stacked against the wall.

Both eyes go back at matching heights a few inches above the concrete, facing each other squarely. Any bracket that has been bent before is replaced.

The technician goes in order: the doorway, the lenses, the aim, then the wire back to the opener. A dead eye is replaced with its partner. Before leaving, the opener is released and the door lifted by hand, because a door that keeps reversing often has a spring or roller problem underneath.

Most sensor calls are quick. If the door needs more than eyes, you get it in writing before anything else happens.

"The opener's dying." Not usually. An opener that won't close on what it thinks is an obstacle is doing its job.

"Take the eyes off and it'll close." It will, and nothing will stop it closing on someone. We repair the eyes; we don't remove them.

"New eyes mean a new opener." A new pair wires into the opener you have.

Belmont to Boone, Rye to Fountain, one call gets a two-hour arrival window, and the technician calls from the road. Nobody guesses at what's wrong over the phone.

Free estimate. Throughout Pueblo County, including Belmont, Sunset Park, Bessemer, Pueblo West, Colorado City, Avondale, Boone, Rye, Fountain.