Garage Door System GuideWhen a garage door refuses to open or close, the fix is often simple, but the diagnosis order matters for safety. CPSC requires that openers made after January 1, 1991 reverse automatically, with an external entrapment protection system added in 1993. Work through power and sensors first, and stop before touching springs or cables, which DASMA says only a trained technician should service.
Start with power and the manual release
Before assuming the door is broken, confirm the opener has power and is engaged. CPSC describes a quick release mechanism that detaches the garage door from the opener so the door can be moved by hand.
To check the door manually, CPSC advises making sure the door is closed, then pulling the quick release to detach it from the opener and moving the door up and down by its handle. If the door moves freely by hand but the motor does nothing, the problem is more likely the opener or its power than the door itself.
Check the photo-eye sensors
A door that opens but will not close is often a sensor problem. DASMA states that since 1993, all openers manufactured for the U.S. must include a second safety reversing feature such as photoelectric eyes, and that these photo eyes should not be installed higher than six inches above the garage floor.
Check that both sensor units point at each other, that their indicator lights are steady, and that nothing blocks the beam. DASMA also notes that if a door does not reverse readily after contacting an obstruction, the opener's sensitivity adjustment may be set improperly, which is a manufacturer-documented adjustment in the owner's manual.
Test door balance
A door that feels heavy or resists moving by hand is likely out of balance, which strains the opener. CPSC describes a properly operating door as balanced, meaning the door stays in place when stopped in any partially open position.
CPSC warns that a severely unbalanced garage door could unexpectedly crash to the floor and possibly strike someone under the open door, and that doors that are not balanced, or that bind or stick, should be serviced by a professional. Do not force a heavy or binding door.
Safety note: never defeat the auto-reverse or sensors
The auto-reverse system exists because closing doors have killed children. CPSC reports that about 73 children between the ages of 2 and 14 have been trapped and killed under automatic garage doors since March 1982, roughly three such deaths per year on average.
CPSC recommends testing the reverse function by placing a 2x4 on the floor of the garage in the door's path, and states that if the door does not properly reverse when striking the 2x4, the opener should be disengaged until it is adjusted per the owner's manual, repaired, or replaced. Do not disable, block, or tape over the photo-eye sensors, and inspect the door and opener every 30 days.
Call a pro for spring and cable issues
If the door is off balance, a spring is broken, or a cable is frayed or off its drum, stop and call a professional. DASMA warns that when the door is down, extension springs are under high tension, and if a spring breaks it may cause injury.
DASMA states plainly that spring systems are dangerous and should be repaired only by trained professionals, and that lift cables should be replaced only by a trained technician. These components store enough energy to cause serious harm, so they are never a do-it-yourself troubleshooting step.