Your garage door starts down, hesitates, and shoots back up. Or it stops six inches off the floor and refuses to budge. The opener clicks, the lights flash, and nothing happens. This is the most common service call we run, and roughly half the time the fix takes two minutes and costs nothing.
Start with the safest checks. If the door is stuck open, do not pull the emergency release while the door is suspended — it will crash down. Unplug the opener first, or have someone hold the door if you must disconnect it.
The photo-eyes are the usual suspect
Two small boxes sit near the floor on either side of the track, about six inches up. One sends an invisible beam; the other receives it. Break that beam and the door reverses instantly. It is a federal safety mandate, and it is the single most common reason a door won’t close.
Check these three things:
- Alignment. Vibration from daily use knocks them crooked. The sending eye usually has a steady amber or green LED. The receiving eye shows green when the beam connects, red or off when it doesn’t. Nudge the brackets until both LEDs are solid.
- Lenses. Spider webs, dust, pollen, or a splash of mud from the last rainstorm will block the beam. Wipe both lenses with a dry microfiber cloth. Do not use glass cleaner — residue attracts more dirt.
- Wiring. The low-voltage wires stapled to the wall and ceiling take a beating from brooms, storage boxes, and seasonal decorations. Look for nicks, pinches, or a wire pulled loose at the opener terminal.
If the receiving eye stays dark no matter how you aim it, the eye itself has failed. They are sold in matched pairs; replace both.
The close-limit screw is set too tight
Every opener has a limit adjustment — usually a white or blue plastic screw on the motor head labeled “Down” or “Close.” It tells the opener how far to travel before it stops. If the screw is turned too far, the door hits the floor and the opener senses resistance, thinks it hit an obstruction, and reverses.
Turn the screw counter-clockwise in quarter-turn increments. Test after each turn. You want the door to kiss the concrete and stop, not slam and bounce. If you have to back the screw out more than two full turns from where it started, something else is binding — stop adjusting and look for mechanical drag.
Force setting masking a mechanical problem
The “Force” or “Sensitivity” dial (often yellow or red) controls how much resistance the opener tolerates before it reverses. Cranking it up will sometimes force a sticky door closed, but you are overriding a safety system designed to prevent the door from crushing whatever is in its path.
Do not increase the force setting as a permanent fix. A door that needs high force to close has a mechanical issue: dry rollers, a bent track, a binding hinge, or a spring problem. Masking it with force adjustment burns out the opener gear set and creates a genuine hazard.
Track and roller issues that feel like sensor problems
A door that binds halfway down will trigger the same reversal as a blocked photo-eye. The opener logic is simple: unexpected resistance equals reverse.
- Nylon rollers crack and flat-spot after five to seven years. A flat spot hits the track radius with a thunk-thunk-thunk you can feel in the floor. Spin each roller with your fingers — it should turn freely, not drag or skip.
- Track brackets loosen over time. The vertical track should be plumb; the horizontal track should slope slightly toward the rear of the garage (about 1/8 inch per foot). A bracket that has shifted inward pinches the rollers.
- Cable drums on torsion-spring doors can slip on the shaft. One side winds faster, the door cocks sideways, and the rollers jam in the track. You will see a gap between the drum and the bearing plate on the loose side.
Lubricate rollers, hinges, and springs with a PTFE-based spray or light synthetic oil. Wipe off excess. Do not use WD-40 — it is a solvent, not a lubricant, and it washes out the factory grease inside sealed bearings. Do not spray the track itself; oil on the track attracts grit and makes the rollers skate rather than roll.
The trolley is disconnected
The red emergency-release cord hangs from the trolley (the carriage that slides on the rail). If someone pulled it — intentionally or by snagging a tall load — the opener runs but the door stays put. The trolley will sit at the motor end of the rail, unlatched.
To reconnect: pull the cord straight down until you hear a click, then run the opener through a full cycle. The trolley will catch the door on the next pass. On some LiftMaster and Chamberlain models you must pull the cord toward the door (away from the motor) to re-engage. Check the sticker on the rail if you are unsure.
Logic board and RPM sensor failures
If the photo-eyes are clean and aligned, limits are correct, force is at factory spec, and the door moves freely by hand — but the opener still reverses or refuses to run — the problem is likely the logic board or the RPM sensor inside the motor head.
The RPM sensor counts revolutions of the output shaft so the opener knows position and speed. When it fails, the opener “loses count” and defaults to safety reversal. On Chamberlain/LiftMaster/Sears units built after 1995, the sensor is a small circuit board clipped to the motor housing with a three-wire plug. It fails from vibration, heat, and age. The logic board itself fails from power surges and moisture.
These are not DIY repairs for most homeowners. The parts are specific to the opener model and manufacture date. A tech can verify with a meter and swap the correct part in one visit.
When to stop troubleshooting and call
- The door is heavy, crooked, or makes a loud bang when you operate it manually. A broken torsion spring or snapped cable is storing violent energy.
- The opener hums but the drive gear doesn’t turn — stripped nylon gear inside. Common on older chain-drive units.
- You have adjusted limits and force, cleaned eyes, lubed rollers, and the door still reverses at the same spot every time.
- The opener is over 15 years old and showing multiple symptoms. Parts availability drops off; a new unit with modern safety encryption and battery backup is often the smarter money.
We carry common residential springs, cables, rollers, and opener parts on the trucks. Same-day service is the normal case across Metro Vancouver. Flat-rate quote approved before work starts. Two-year workmanship warranty on repairs.
Next step: If the safe checks above didn’t solve it, call 778-873-7282 or email info@upanddowngaragedoors.ca. We’ll tell you what we’re sending and what it costs before the truck rolls.