If your garage door opens fine but won't go back down (or comes back up when you try to close it), the cause is almost always one of three things: misaligned photo-eye safety sensors, an obstruction in the door's path, or the opener's close-limit setting needs adjustment. All three are 5-minute DIY fixes 90% of the time.
The #1 cause: sensor misalignment
Photo-eye safety sensors are required by federal law on every garage door opener manufactured since 1993. They sit about 6 inches off the floor on each side of the door, facing each other. If they're not aligned, the door won't close.
Walk over and check the LED indicators on both sensors. Both LEDs solid = working. One blinking = misaligned. Both off = failed. Realign by gently rotating until both LEDs go solid.
The #2 cause: dirty sensor lenses
Spider webs, pollen, dust, or salt-air residue on the sensor lens can break the invisible beam between the two sensors — the door interprets that as an obstruction and won't close.
Wipe both lenses with a soft dry cloth. Don't use water or cleaning sprays. Test the door.
The #3 cause: obstruction in the path
Anything between the two sensors that crosses the beam will prevent the door from closing. Check for: lawn equipment, sports gear, bicycles, garbage cans, kids' toys, or even tall weeds growing in the path. Clear the area.
Less common: limit switch out of adjustment
The opener has 'open' and 'close' limit switches that tell it when to stop. If the close-limit is set too far (past the floor), the opener tries to close past the floor, hits resistance, and reverses upward to protect itself.
Limit adjustment screws are on the opener housing — refer to your opener manual. Usually a 1/4 turn fixes it.
Less common: opener force setting too sensitive
The 'force' setting controls how much resistance the opener will tolerate before assuming there's an obstruction. If set too sensitive, normal closing resistance triggers a reverse.
Force adjustment is also on the opener housing. Increase slightly until normal closing works without triggering reverse.
Rare: actual opener failure
If sensors are clean and aligned, no obstructions, limits are correctly set, and the door still won't go down — the opener itself may have failed. Diagnostic call: $149. Common repairs: $145-$295.
Common questions.
Why does my garage door open but not close?
Almost always a sensor problem. The federal-required photo-eye safety sensors must see each other clearly. Misalignment, dirty lenses, or an obstruction in the path will all cause this behavior.
How do I bypass the safety sensors?
You shouldn't. Sensors are required by federal law (UL 325, 1993) on every opener since 1993. Bypassing them is illegal and dangerous — children, pets, and vehicles can be crushed. Fix the sensors instead.
Why does my garage door close partway then come back up?
Either a sensor detecting an obstruction mid-close, or the opener's force setting is too sensitive (it interprets minor close-resistance as an obstacle). Check sensors first; if they're fine, the force-adjust screw on the opener can be turned slightly to fix it.
Can the cold cause a garage door to not close?
In Florida this is rare but possible. Extreme cold thickens lubricant on the spring and rollers, increasing the resistance the opener encounters, which can trigger the force-reverse. Lubricate with a silicone-based spray rated for temperature.
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