One of the most common service calls we get everyday is for the garage door not closing. Here is a quick guide to help you fix the problem:
1.- Check the Opener Sensors.
If the garage door tries to go down but it goes back up (some start flashing the lights and you can hear a clicking noise on most Liftmaster, Chamberlain and Craftsman) it might be the sensors.
* Please make sure nothing is on the way of the sensors.
* Make sure they are aligned. They have to see each other in order to go down.
* Clean the lense of the photo eyes.
* Check the wires to see if they have not been chewed up by anything.
* Check the back of the opener to make sure sensor wires are not loose.
* Sometimes sun can "block" the sensor eyes. They might need to be moved or make some shade.
2.-Lock is ON.
Some overhead openers have a lock button or some people call it vacation mode. If your remotes don't work but your wall button does. Try pressing and holding the Lock Button for a couple of seconds until lights stays ON. If the Light is Flashing, it is a good indication it is in LOCK MODE.
3.-Force Settings are too Sensitive.
On the Back of the opener there are 2 force settings: One for Up and another for Down. You can try to raise the Down force setting a little -Consult your Owners Manual. *If you are not comfortable doing this Please Call a Technician.
If one side of the garage door is hanging Please Call a Technician. You have a crashed door.
I hope this helps.