Garage Door Won't Close — What's Actually Going On
A garage door that refuses to close is more than an annoyance — left open, it's a security gap, and in extreme heat or cold it's an energy problem too. It almost always comes down to one of seven things, and which one it is changes how urgent the situation actually is.
1. A Blocked or Misaligned Safety Sensor
Every garage door opener made since the early 1990s has a pair of photo-eye sensors near the floor that beam an invisible line of light across the doorway. If that beam is broken — by an object, or by a sensor that's been bumped out of alignment — safety standards require the opener to refuse to close rather than risk coming down on something. This is the single most common reason we're called out for a door that won't close, and it isn't a flaw; it's the safety system doing exactly what it's built to do.
2. Something Sitting Near the Sensor Line
A trash can, a delivery box, or a leaf pile can trigger the same response as a genuine obstruction under the door — the object doesn't need to be in the door's path itself, just near the sensor beam.
3. Damaged or Dirty Safety Sensors
Grime, a cracked lens, or a sensor that's taken a hit from a car bumper or lawn equipment all stop the beam from reading correctly, even with a clear doorway. From the outside this looks identical to a simple misalignment, which is part of why it needs an actual look rather than a guess.
4. The Down-Limit Setting Has Drifted
The opener has an internal setting for where "fully closed" actually is, and that setting drifts gradually with age and vibration. When it does, the opener thinks the door has reached the floor before it has, and stops or reverses short. This is a calibration inside the opener, not something to diagnose by trial and error — set wrong in the other direction, the door comes down with too much force instead of too little.
5. A Broken Spring
A broken torsion or extension spring doesn't just stop a door from opening — it can stop it from closing correctly too, since the spring is what counterbalances the door's weight. A loud bang at some point, a door that looks crooked, or one side moving faster than the other are the signs. A door with a broken spring shouldn't be operated at all until it's repaired; the imbalance strains the opener and the door can come down unevenly.
6. Remote Interference
Older fixed-code remotes and openers can occasionally pick up a signal from a nearby system on the same frequency, which shows up as the door starting to close and then reversing, or ignoring the close command entirely. This is a receiver and signal issue, unrelated to anything mechanical.
7. A Mechanical Issue in the Opener or Track
A binding track, a worn roller, a bent rail section, or a worn drive gear inside the opener can all stop the door short of fully closing. These usually build gradually — some resistance or noise in the days before the door stops closing altogether.
How Urgent Is This?
Sensor and obstruction issues (causes 1–3) are inconvenient but not dangerous — the door just stays open until the beam is clear. A drifted down-limit or a mechanical issue (4, 7) is worth addressing soon, since both tend to get worse rather than resolve on their own. A broken spring (5) changes the calculation entirely: stop using the door and call, because an unbalanced door under partial spring tension is a real safety risk, not just an inconvenience.
What a Technician Does
A service call for a door that won't close starts with the sensors — alignment, the beam path, the lenses — since that's the most common cause by a wide margin. From there it moves to the down-limit setting, the springs, and the track and drive components until the actual cause is confirmed rather than guessed at. You're told what's wrong and what it costs before anything is touched.
Real Gate & Garage Door provides same-day garage door repair across Los Angeles and Southern California, seven days a week. Call (818) 915-5715 or text a photo of your door for a free diagnosis.
Frequently Asked Questions
Is it safe to leave a garage door open overnight if it won't close?
Not from a security standpoint. Treat it as urgent — call, and if you can't get same-day service, secure the opening some other way in the meantime rather than leaving the house exposed.
Why does my garage door start closing and then reverse?
Almost always the safety sensors reading an obstruction — real or false — at that exact point in the door's travel. It's less commonly a down-limit setting that's drifted.
The opener's light is on but the door won't close. Does that rule out a power problem?
Yes. If the opener has power, the cause is downstream of that — sensors, the down-limit setting, or a mechanical block — not an electrical failure.
Can cold weather stop a garage door from closing properly?
Temperature swings can affect timing on some openers, but a door that stops closing altogether usually has a specific cause worth diagnosing rather than something to wait out until it warms up.
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