Why Your Garage Door Won't Close

A garage door that will not close is one of the few home problems that leaves your house physically open. It is also, more often than not, free to fix. Before you call anyone, work through these in order.

Start with the safety sensors

Since 1993, every residential opener has had two photo-eye sensors mounted near the floor on each side of the opening, about six inches up. They project an invisible beam across the doorway. If anything breaks that beam, the door refuses to close, which is exactly what should happen when a child or a pet is underneath.

The catch is that the sensors cannot tell the difference between a real obstruction and a misaligned partner. Nine times out of ten, that is your problem.

Check them in this order:

• Look at the indicator lights. Each sensor has a small LED. Both should be lit and steady. One blinking or dark means they are not seeing each other.
• Clear the path. A trash bin, a bike wheel, a snow shovel leaning against the wall. Also look for a cobweb across the lens, which is enough to break the beam.
• Wipe the lenses. Dust and road film build up over a season. A dry cloth is enough.
• Nudge one back into line. Loosen the wing nut on the bracket, tilt the sensor slightly until the light goes solid, then tighten. They only need to be pointed at each other.
• Check for direct sun. In low winter light, sun hitting a lens can wash out the beam. If your door only misbehaves at the same time of day, that is why, and a small shield fixes it.

Then check the travel limits

If the sensors are fine, the door may be closing all the way and then reversing back up. That is a different fault: the opener thinks it hit something.

Openers have a close-limit setting that tells the motor where the floor is. If it drifts, the opener drives the door into the concrete, senses resistance, and reverses because it assumes it struck an obstacle. Most units have limit adjustment screws on the motor housing marked up and down, and small increments are the right approach.

Check the track and rollers

If the door binds partway down and reverses, look along the vertical tracks for a dent, or at the rollers for one that has jumped its channel. A door catching on a bent track behaves exactly like a door hitting an obstruction, because as far as the opener is concerned it is.

This is also where a cable problem shows up. If one side of the door sits visibly lower than the other, or the door looks crooked in the opening, stop. That is a cable off its drum, and running the opener will make it worse.

Try the wall button versus the remote

Quick diagnostic. If the door closes from the wall button but not the remote, you have a remote or receiver issue rather than a door issue. If neither works but the opener hums, the trolley may be disconnected from the emergency release cord.

When to stop and call

Everything above is safe for a homeowner. Stop at any of these:

• A visible gap in the spring coil above the door
• The door sitting crooked, or one side lower than the other
• A frayed or slack cable
• The door feeling extremely heavy when lifted by hand

Those are tension problems, and the components involved store enough energy to cause serious injury. A door that will not close also means an unsecured house, which is a reasonable thing to call about outside normal hours.