First, split the fault in two
Before you touch anything, watch the door try. There are two completely different faults hiding behind “it won't close”, and telling them apart saves you an hour:
- The door starts down and reverses. The opener is working, and something is telling it to stop. That is nearly always the safety sensors, the close limit, or the down-force setting.
- The door does nothing at all. Now you are looking at power, the wall console, the remote, or a mechanical failure between the motor and the door.
Everything below is in the order we would actually work through it, cheapest and most likely first.
1. Watch the opener light
Press the wall button and watch the bulb in the opener head. On virtually every opener built in the last thirty years, a light that blinks instead of coming on steady is the opener saying it cannot see a clean beam between its two safety sensors. That single observation resolves more “won't close” calls than everything else on this page put together.
2. Clear the beam, then look again
The two photo eyes sit at the bottom of the tracks, no more than six inches off the floor. Anything crossing the line between them stops the door: a bin that has drifted, a bike wheel, a bag of mulch, a coiled hose, a broom that slid down the wall. Move it and try again before you assume the sensors are broken.
3. Clean the lenses
Both lenses need a wipe with a dry cloth. In this part of Georgia the two things that film them over are spring pollen and spider webs — a single web strung between the eye and its bracket is enough to break the beam, and late March is reliably our busiest stretch for doors that suddenly stop closing for no visible reason.
4. Read the sensor LEDs
Each photo eye has a small indicator light. What you want is one steady light on each sensor. A light that is off, or flickering as you move, means the pair are not pointed at each other. Loosen the wing nut on the bracket, move the sensor by tiny amounts until the light goes solid, then nip the nut up without shifting it. Do this on the receiving eye — usually the one whose light is the fussy one.
5. Consider the sun
If your door faces roughly west and it closes fine all morning but refuses in the late afternoon, nothing is broken. Low sun shining straight into the receiving eye washes out the beam it is looking for. A small shield over the lens, or swapping which side the sending and receiving eyes are mounted on, fixes it permanently.
6. Try the hold-to-close test
Press and hold the wall button rather than tapping it. On almost every opener made since 1993, constant pressure on the wall button overrides the photo eyes, and the door will close for as long as you keep your finger down. If the door closes that way, you have proved the sensors are the fault and the opener itself is fine.
7. Check the close limit and the down-force
If the sensors check out and the door still reverses the moment it touches the floor, the opener is over-travelling: it keeps driving after the door is already down, reads the resistance as an obstruction, and backs off. That is the close-limit setting. If it reverses partway down with a clear track, that is usually down-force. Both are adjustments on the opener head rather than new parts — but they are also the settings that decide how hard the door pushes on the way down, so they are worth getting right rather than winding up until the symptom disappears.
8. Check the lock button on the wall console
Most wall consoles have a lock or vacation button. Pressed — often by a coat sleeve — it disables every remote and, on some models, the door itself. It is a thirty-second check and it closes a surprising number of calls.
What the door is telling you, in one table
| What you see | Most likely cause |
|---|---|
| Opener light blinks, door won't go down | Safety sensors — beam broken, dirty or misaligned |
| Reverses the instant it touches the floor | Close limit set too low, or down-force too tight |
| Goes most of the way, then reverses | Obstruction or a dent in the track, or down-force |
| Closes only while you hold the wall button | Confirmed sensor fault — the override proves it |
| Motor runs, door doesn't move | Snapped spring, stripped drive gear, or a broken trolley |
| Nothing at all, motor silent | Power, the wall console lock, or the logic board |
When it stops being a five-minute fix
If the motor runs and the door does not move, stop. Two things cause that, and both need a technician: a broken torsion spring, which leaves the door far too heavy for the opener to lift, or a stripped drive gear inside the opener head. Running the opener again to see if it will catch is how a cable jumps its drum and turns a one-part job into three.
The same goes for a door that is visibly crooked in its opening, a cable hanging slack, or a visible gap in a spring on the shaft above the door. Those are not adjustments. They are stored energy in the wrong place.