If your garage door goes down a few inches and then goes back up, or the opener light blinks and the door will not close, the safety sensors are the first thing to check. They are the two small eyes near the floor on each side of the door, and they must see each other. In Arizona, dust, spider webs and afternoon sun are common reasons they stop working. You can fix this in about 10 minutes, but never touch the springs or cables.
Time: about 10 minutes. Skill: easy.
What do the safety sensors do?
Two sensors sit about 4 to 6 inches off the floor, one on each side of the door opening. One sends an invisible beam and the other receives it. If something blocks the beam, the door will not close, or it reverses. This protects people, pets and cars.
How do you fix garage door sensors?
- Look at the lights. Each sensor has a small LED. Usually both should be steady. If one is dark, blinking, or dim, that is your problem.
- Clear the path. Move anything blocking the beam: a box, a bike, a hose, a stray leaf.
- Clean the lenses. Wipe each lens with a soft, dry or slightly damp cloth. Dust storms, spider webs and hard water spots from sprinklers all cover lenses.
- Check the wires. Follow the thin wire from each sensor up the wall to the opener. Look for a pinch, a cut or a loose connection. Sun and heat can make old wire brittle.
- Check alignment. A sensor that has been bumped by a car, a trash can or a kid's bike can point slightly off. Loosen the wing nut or bracket just enough to move it. Nudge the sensor until its LED goes steady, then snug the nut again. Do not overtighten.
- Handle sun glare. Direct low sun shining into the receiving sensor can confuse it, usually in the morning or late afternoon. If the door only fails at certain times of day, shade the lens with a short cardboard tube or a small hood made from a plastic cup, taking care not to block the beam itself.
- Test it. Close the door with the remote or wall button. Then put a roll of paper towels flat on the floor in the path. The door should touch it and reverse. If it does not reverse, stop using the door with the opener and call a pro.
Never touch the springs, cables or brackets
A garage door is heavy, and the springs and cables hold a great deal of tension. They can cause serious injury. Do not adjust, loosen or remove the springs, the cables, or the brackets at the bottom corners. These are pro-only jobs.
If a spring is broken, you may see a gap in the coil or hear a loud bang. Do not try to lift the door. A broken spring leaves the door much heavier than it looks.
When to call a pro
Call a pro if the sensors still blink after cleaning and aligning, the door is crooked, off its track, or sagging, a cable looks frayed, the opener hums but the door does not move, or you suspect a broken spring. A garage door that will not close is also a security problem, so you will want it fixed quickly. Here are local garage door companies in the directory, with phone numbers:
Some list emergency or same-day service. Check any contractor's license at roc.az.gov, and use the helper if you are not sure who to call.
Questions people ask
Why does my garage door go down and then back up?
The sensors are most likely seeing something in the way or are misaligned. Clean the lenses, check that both LEDs are steady, and realign the sensor that is dark or blinking.
Can I close my garage door manually if the sensors are broken?
Many openers let you hold the wall button down until the door closes, even with the sensors blocked, but this varies by model, so check your manual. Do not pull the red emergency release cord with the door open unless you know the springs are intact, because a door with a weak or broken spring can drop fast. If the door feels heavy or uneven, call a pro.
Why does my garage door only fail in the afternoon?
Sun glare on the receiving sensor is a common cause in Arizona. Shading the sensor or adjusting its position often solves it.
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