Garage door sensor not working? Why your door turns around and goes back up

Look down at the bottom of each track and you'll find a small box on a bracket. The two boxes are a matched set: one shines an invisible line across the opening and the other watches for it. While your door is coming down, the opener keeps checking that the line is unbroken, and the moment it isn't, the door reverses.

So when your door won't close, the opener isn't broken. It believes something is in the doorway, and our job is to find out whether anything really is, or what is fooling it.

Here is what we tend to find, most common first.

1. Gear parked in the doorwayA trailer tongue, a mower deck, the wheel of a side-by-side or a stack of feed bags sitting a little too far forward. Anything in that low strip between the boxes reads as a person.
2. Haze on the lensesHumid summers leave a damp film on everything in a closed garage, and dust sticks to it. A clouded lens loses the line first at dusk, when the light outside drops.
3. A box knocked sidewaysTrailers, mowers and ATVs catch the brackets on the way in and out. A bracket that has been bumped more than once is replaced with a stiffer one rather than bent back again.
4. The evening sunA west-facing garage can take the setting sun straight into the receiving box. If the trouble only shows up in the late afternoon, that is the likely reason.
5. Wire troubleA staple through the thin two-strand wire, a splice hidden behind shelving, or corrosion where humidity has worked into a connection. If both lights are out, the wire is our first suspect.

If both lights glow, nothing is in the way, and your door still comes back up, the eyes are off the hook. A door that turns around right at the floor usually has its close limit set too long. One that turns around halfway, and feels heavy when you lift it by hand, is often telling you a spring is weakening.

Ice storms bring a cousin of this problem. Freezing rain can glue the bottom seal to the slab overnight, the opener heaves against it and trips out. That calls for seal and balance work; fresh sensors wouldn't change a thing.

Sometimes an eye really has died: water inside the lens, a crack from a mower strike, or a board fried by a storm surge. We replace the pair together with eyes built for your opener, because they rarely cross over between brands.

Damaged wire is replaced in one continuous run, kept clear of the trailer's path, and held with insulated clips so the same trouble doesn't return next season.

Mounting gets a hard look too. The two boxes belong at matching heights, a hand's width or so above the concrete, aimed squarely at each other on brackets stout enough to shrug off a bump.

Lights first, then the line between the boxes, the lenses, the aim and the wire back to the motor. Before we leave, the opener is unhooked and the door raised by hand, because a sensor call sometimes hides a spring on its last legs, and you'll hear about it if so.

Most of these are short calls. The long ones tend to be doors that had a balance problem brewing well before the eyes spoke up.

"The motor must be going out." Rarely. The blinking light is the opener telling you the eyes are unhappy, not that its own motor is failing.

"We'll just leave them unhooked." Please don't. With the eyes out of the loop, nothing stands between a closing door and whoever steps under it. Putting them back in service is usually quick.

"Sensors mean a whole new opener." Not at all. New eyes connect to the motor unit you already own.

Call from Rountree, Galloway, Nixa or Ozark and tell us what the door's doing. We'll give you a couple of hours to be around and ring when we're headed over.

Free estimate. Throughout Greene County, including Rountree, Phelps Grove, Galloway, Nixa, Ozark, Republic, Battlefield, Strafford, Willard.