How to Troubleshoot a Liftmaster That Won't Close

Ensure the garage door opener has power by plugging in a lamp into the mechanism's outlet. If the lamp lights, the power supply is working correctly. Reset the breaker protecting the garage door opener's circuit if the outlet appears to be broken.

Allow 15 minutes for the motor to cool down. Repeated, frequent use causes the motor to warm up and in rare cases overheat. While the motor cools down, check that the spring of the garage door is still intact. A damaged spring stops the door opening and closing.

Look at the garage opener light when you try to close the door; the light blinks if the safety sensors are detecting an obstruction. Make sure there are no objects in the doorway and check that the amber indicator lights in the sending and receiving sensor are glowing. No indicator lights indicate a power or wiring problem, no light on the receiving eye only indicates a problem with the alignment between the sending and receiving sensors.

Turn the down force adjustment dial, located on the back panel of the motor unit, clockwise one marking and try to close the door again. Keep turning the dial by increments until the motor is programmed to apply enough closing force. Each garage door requires a different amount of force to open and close.