My garage door wouldn’t go down. You know the drill–you push the button, the door goes down for a few seconds, then reverses course, and maybe your opener blinks at you a few times. Not all garage door openers do the blinky thing though.
The reason is simple. The safety sensors couldn’t see each other, so they assumed something, or worse yet, someone, was in the way, in danger of being hit by the door, and made the opener reverse course. As annoying as a door is that won’t close, a door that mashes stuff is a lot worse.
My sensors couldn’t see each other because we’d moved some stuff around and, I guess we bumped one of them.
I tried to eyeball it and didn’t get it right. Good sensors have LEDs on them that indicate when the sensors are aligned. On mine, both are green, but on some, one light may be amber and one may be green. On mine, both lights go out when they’re not aligned. Of course that varies too–sometimes only one of the lights go out. But, at any rate, you can tell when the sensors aren’t lined up because you don’t have two lights.
I accidentally fixed it by moving something else and bumping one of the sensors again. The goofy thing is, the sensors didn’t look like they were even close, eyeballing it. Admittedly I’m a lousy golf shot, but these sensors were clearly 10 or maybe even 15 degrees off. But the lights were on, so I went with it. And, indeed, the door worked fine. Sometimes it’s better to be lucky than good.
If you’re not as lucky as me, fixing them isn’t too hard. There’s considerable play in most sensors even when they’re mounted. Slowly move one sensor through its full range of motion–even the portions of the range of motion that can’t possibly be right–and stop when the light comes on. It may not look right to your eye, but that’s why the sensors have LEDs. From five or six feet up, we can’t see what the sensors see.