How to Fix a Chain Drive Garage Door When It Won't Open

A malfunctioning garage door opener can leave you in the cold.

A malfunctioning garage door opener can leave you in the cold.

Having an automatic door opener in your garage is a great convenience, but you have to give the opener and all its parts regular maintenance, or it can flummox you with erratic behavior. One such quirk is a refusal to open the door as commanded: When this happens, you could get locked out of the garage. This can indicate a problem with the motor, but it might have other causes, including a bent, misaligned or loose track or sensors that are dirty or out of alignment. Motor problems often require professional help.


Make basic checks first. Ensure that the unit is plugged in, the door isn't locked and, if you are using a remote, that the remote has batteries. Check the breaker controlling the door opener, and reset if it it's tripped. You should also ensure that the door is engaged with the trolley. Someone might have pulled the emergency cord.


Disengage the door from the trolley by pulling the emergency cord if none of the basic checks reveals a simple explanation for why the door won't open. Try to open the door manually. If it won't move, look for a bent or loose track or a bent roller. Any defective part you find will have to be repaired or replaced. It may also help to spray lubricant on the door rollers.


Press the remote or the wall-mounted start switch, listen to the motor and watch the movement of the chain. If the motor hums, but the chain doesn't move, that indicates a problem with the motor. If the motor works but the chain doesn't move, the chain sprocket may need servicing. If nothing happens at all, the safety sensors may be out of alignment.


Check the sensors. You should see a steady light on both of them, which indicates that they are aligned and working properly. If one or both lights are off or flashing, look for dirt, cobwebs or leaves in front of the sensor lenses, and clean the lens if necessary. If the lights still flash, manually realign them until the light is steady. This may involve tightening one or both of the vertical door tracks with a screwdriver or wrench.


Try the door again after servicing the sensors. If nothing happens when you press the start switch, there may be an electrical disconnection inside the motor casing or in the house circuitry. Look inside the motor for loose wires. If you find one, unplug the door opener before tightening it. Check the circuit wire for connection problems, using a voltage tester, if you can't find any problems inside the motor.


Consult a professional if the opener hums but the chain doesn't spin. This could be the result of a faulty capacitor. A test will reveal whether or not it needs to be replaced, but the test involves discharging the capacitor, which can be dangerous. If the motor works, but the chain doesn't move, you should also consult a professional. The repair may involve disassembly of the motor.

Things You Will Need

  • Wrench or screwdriver
  • Voltage tester


  • If the floor underneath the door isn't level, the door can become misaligned in the tracks and fail to move. It will work again after you realign it, but the problem will recur unless you fix the floor.


  • If you can hear the motor trying to open the door, but the door won't budge, stop the motor immediately to prevent it from burning out.

Photo Credits

  • Jupiterimages/ Images
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