Garage Door Opens, but will not close!?!
Each of these units should have a little green light on them. The light on the sender is always on when there is power to the opener, that is, when the opener is plugged in, not just when you try to operate it. The green light indicates it is sending. Now, the receiver, on the other hand, will only have it‚Äôs light on when it is receiving, that is, when it is picking up the signal from the sender.
So‚Ä¶with the opener plugged in, look at each unit. If one of the lights is on but not the other, then you know which one is the sender, the one that‚Äôs has its green light on. You may want to mark it for future reference. Then, you will need to adjust both of them until both lights are on. It‚Äôs not as hard as it sounds. Each unit looks like a small camera, so simply loosen the set-screw of one or both, point the lens of one towards the lens of the other, then re-tighten the set-screws.
Now, if neither one lights up, the problem is a bit more in-depth. Either you have a loose wire, or one of the units is broke. Each one has two wires, and your owner‚Äôs manual will cover their hookup. Check to make sure they are properly hooked up to the opener unit, and that they are not broken anywhere between the opener and the sender or receiver. If that does not work, either the sender of receiver could be bad. At that point you may want to call Sears, or whoever installed the system.
Good luck, and feel free to post the solution or additional questions.