Why your garage door reverses before it closes

A garage door that starts to close, changes its mind and runs back up is one of the most common faults in Australian houses, and it is almost always one of four things: the safety beams cannot see each other, the force setting is too sensitive for the door's current condition, the travel limit is set past where the door actually stops, or something in the track is physically resisting. The good news is that the door is telling you which one, if you know how to read it. This guide works through them in the order a technician would.

First, note exactly when it reverses

The timing is the diagnosis.

• Reverses immediately, before it moves at all, or within the first few centimetres. This is nearly always the photo-electric safety beams.
• Reverses partway down, at the same spot every time. Something physical. An obstruction, a bent track, a seized roller, a hinge catching.
• Reverses at the very bottom, just as it touches down. Down force or down travel limit.
• Reverses at a random point that changes. Intermittent beam alignment, a marginal force setting, or a door that is dragging inconsistently.

Watch it two or three times before you touch anything. Guessing costs more time than watching.

Safety beams

Photo-electric safety beams sit about knee height or lower on each side of the opening, one sending an infrared beam and one receiving it. Break the beam and the door refuses to close, or reverses if it is already moving. That is the entire point of them, and they are not optional equipment to be bypassed.

What goes wrong, in rough order of frequency:

• Dust, cobwebs and salt film on the lens. Wipe both lenses with a soft dry cloth. In coastal areas this is a routine maintenance item, along with everything else in Colorbond doors and coastal corrosion.
• Knocked out of alignment. A bike, a bin, a mower or a car door. Most units have indicator LEDs: typically one steady light on the sending unit and a light on the receiver that goes out or flickers when the beam is broken. Loosen the bracket, move it slowly until the receiver reads steady, then tighten.
• Direct sunlight into the receiver. Late afternoon sun straight down a west facing driveway can swamp the sensor. If the fault only happens at a particular time of day, that is your answer, and a small shade or a slight repositioning fixes it.
• Damaged or pinched wiring. Follow the cable from each sensor back to the opener head and look for staples through the insulation, rodent damage or a terminal that has vibrated loose.
• A genuine obstruction. Look before you assume. A pot plant, a hose reel, a cat.

Never tape a sensor to a wall pointing at nothing, and never bridge the terminals. That converts a safe door into a closing hazard, and the door is heavy enough to matter.

Force settings

Openers monitor how much effort they are using. If the door meets more resistance than the down force setting allows, the opener treats it as an obstruction and reverses. This is a safety feature working correctly, and the correct response is to find the resistance, not to wind the force up.

Resistance builds up from:

• Dry, dirty or bent tracks.
• Worn rollers that no longer roll. This is a bigger contributor than people expect and is covered in replacing garage door rollers.
• A perished bottom seal dragging on the slab.
• A door out of balance because the spring has weakened. Test it: pull the emergency release, lift the door by hand to halfway and let go. It should stay put. If it drops or rises, the spring needs attention from an installer, as set out in torsion spring replacement.
• Cold weather stiffening seals and lubricant.

Only after the door moves freely by hand should you touch the force adjustment, and then only in small increments, testing the safety reverse afterwards with a solid object laid flat across the opening. If the door does not reverse cleanly off that object, the setting is wrong and the door is unsafe.

Travel limits

The down limit tells the opener where the floor is. If it is set too far, the opener keeps driving after the door has landed, the force spikes, and the opener reverses because from its point of view the door has hit something. This is the classic cause of a door that reverses only in the last few centimetres, and it often appears after a new floor coating, a new bottom seal, or a slab that has moved.

Limits are adjusted differently on every model. Find the manual for your specific opener rather than following generic advice, set the down limit so the bottom seal just compresses, then re-test.

Physical obstruction and track damage

If it reverses at the same height every time, go and look at that height. With the door open and the power off at the wall, run your eye and your hand along both tracks. You are looking for:

• A dent or a flat spot where something hit the track.
• A track bracket that has pulled away from the timber or the masonry.
• A roller stem that is bent, or a roller that slides instead of rotating.
• A hinge that has torn its fixing out of the panel.
• Cable that has jumped a groove on the drum, or is frayed. Frayed cable is a stop-work item, and the reasons why are in tracks and cables.

Do not straighten a track by hitting it with a hammer while the door is closed and the spring is loaded. If a track is damaged badly enough to need reshaping, it usually needs replacing, and the load has to come off the system first.

When it is the opener itself

If the beams check out, the door moves freely by hand, the limits are correct and it still reverses, the fault may be in the opener. Common causes are a failing logic board, a worn drive gear that slips under load, or a trolley that is not engaging cleanly with the rail.

At that point the decision is repair or replace. Parts for current models are usually available; parts for a twenty year old unit often are not. If you are replacing, the specification that matters is in the motor buying guide, and the used market is worth a look via the motors and openers category before you pay retail.

The order of operations

Clean and align the beams. Test the door by hand with the power off. Fix whatever is dragging. Check the limits. Only then touch the force settings. Re-test the safety reverse when you are done, every time.

If the by-hand test shows the door is out of balance, stop and book someone. Spring and cable work is where a nuisance fault becomes a serious injury, and the installer and repairer directory will find you a business in your state.