Garage Door Opener Runs but Door Doesn't Move - Troubleshooting Guide

You can hear the opener running. Motor is going, light comes on, everything sounds like it's doing something. But the door just sits there. Doesn't budge.

This one is actually useful to diagnose because the fact that the opener runs narrows things down. The motor is getting power. The problem is in what happens between the motor and the door.

Here's every realistic cause in order of how common they show up.

Disconnect cord was tripped and never re-engaged

This is probably the most overlooked cause and it's the first thing worth checking because it takes ten seconds.

That red cord hanging from the rail - pulling it disconnects the trolley from the drive mechanism so the door can be operated manually during a power outage. Once it's disconnected, the opener runs fine but the trolley just slides back and forth without moving the door. Motor sounds normal. Nothing happens.

Look at the trolley on the rail. Is it connected to the door arm or is it floating free? On most systems there's a visible hook or lever that should be engaged. To re-engage: manually move the door to the fully closed position, then run the opener on close - on most models the trolley hooks back in automatically when the drive catches it.

If nobody pulled the red cord deliberately, check if maybe it got bumped or snagged on something being moved through the garage.

Stripped drive gear

Inside the opener motor housing there's a plastic gear - sometimes called the drive gear or idler gear - that transfers the motor's motion to the chain, belt, or drive screw. It's made of plastic on purpose. When something jams or there's too much load, this gear strips out instead of burning up the motor.

When it strips, the motor runs completely normally - you hear it, the shaft turns - but nothing transfers to the drive mechanism. Door doesn't move.

Unplug the opener and pop the cover off the housing. Look at the main plastic gear near the motor shaft. Teeth chewed up, worn smooth, plastic debris inside - that's the stripped gear.

Replacement kits are $15-35 on Amazon depending on brand. LiftMaster, Chamberlain, Craftsman, Genie all have model-specific kits. YouTube has walkthroughs for most common models. Not a difficult repair if you're mechanically comfortable.

One thing to note: if the gear stripped because the door springs are badly out of balance and the opener was carrying too much load, replacing the gear without fixing the springs means you'll be replacing the gear again in a year or two.

Broken torsion spring

When a spring breaks, the door becomes extremely heavy - the opener can no longer move it. But in some cases the opener still tries and you hear it running before the force protection kicks in.

Look above the door at the horizontal spring on the metal bar. Any gap in the coil? Visible break? That's a broken spring.

Don't keep running the opener against a door with a broken spring. You'll burn out the motor or strip the gear. The spring needs to be fixed first before the opener can do its job.

Spring replacement - call someone. Torsion springs are under serious tension and replacing them without proper winding bars and experience is genuinely dangerous. $150-250 for a pro to handle it is the right move.

Belt or chain off the drive sprocket

If yours is a belt drive or chain drive ↗ opener, the belt or chain needs to be properly seated on the sprockets at both ends of the rail. If the belt snapped, came off, or the chain jumped the sprocket, the motor runs freely but nothing moves.

Look along the rail while the opener runs. Is the belt or chain moving? If the belt is broken you'll often see it hanging loose or piled up somewhere along the rail. If the chain jumped the sprocket, you might see it sitting wrong at the motor end.

Snapped belt needs replacement - belts for common opener brands run $20-40. A chain that jumped the sprocket can sometimes be reseated if there's no damage, though finding out why it jumped in the first place matters - usually chain tension was too loose.

Trolley jammed on the rail

The trolley can jam at a specific point on the rail - debris on the rail, a bent section, a stripped trolley carriage. When it jams, the motor runs and strains against it, but the trolley doesn't move.

Watch the trolley while the opener runs. Is it moving at all? Trying to move and stopping? Any visible damage to the rail or trolley carriage?

Minor obstructions on the rail - debris, dried grease buildup - clean and lubricate the rail. A damaged trolley carriage needs replacing - they're available as parts for most opener brands.

Opener in vacation lock mode

Some openers have a lock feature - sometimes called vacation lock or door lock - that disables the remote and can disable operation from the opener itself. Usually activated by holding the wall button for several seconds.

If the light pattern on the opener is different than normal, or if the wall button doesn't work either, check whether lock mode got activated accidentally. The process to deactivate it varies by brand - usually holding the wall button again for a few seconds. Check your opener's manual if you're not sure.

Motor capacitor failing

The capacitor gives the motor its starting burst of power. When it fails, the motor hums or makes a brief sound but can't actually turn. Sounds like it's running but isn't generating any real motion.

Test: have someone give the door a firm upward push right when the opener activates. If it suddenly starts moving with that assist, the capacitor is likely the issue - you're providing the starting torque the capacitor can't.

Capacitors are cheap - $10-25 for the part. They store charge even when unplugged, so if you're not familiar with discharging capacitors safely, have a tech swap it.

Logic board sending signals to the motor but not the drive

Less common but the board can fail in a way where the motor gets power but the output that controls the drive mechanism doesn't work correctly. The motor runs, nothing moves, and there's no obvious mechanical cause.

If you've gone through everything above - trolley engaged, gear intact, spring not broken, belt/chain in place, no jam - and it's still happening, the board is worth having someone look at. Especially if there are other weird behaviors like lights not working right or settings not holding.

Quick order to check things

Red cord - is the trolley actually engaged to the door arm?

Spring above the door - any gap or break?

Open the housing - does the drive gear look chewed up?

Belt or chain - is it on the sprockets and intact?

Watch the trolley while the opener runs - is it moving at all?

Try the push-assist test - does pushing up help the door move?

None of the above - wall button test, then logic board.

Trolley disconnect and stripped gear cover probably 70% of cases where the opener runs but nothing moves. Spring is the third most common. Check in that order and you'll find it most of the time.

GarageDoorRepairz if you need someone to come look. We'll figure it out fast.