Why is my garage door safety sensor blinking green?

When your garage door safety sensor is blinking green, it almost always means the receiving sensor is not getting a solid, uninterrupted infrared beam from the sending sensor. The green light is on the receiver side, and its job is to stay solid when it sees the beam clearly. A blinking green is the system's way of saying I am trying to see the beam but I can't lock onto it. The most common cause is simple misalignment. The brackets are near the floor and get bumped by cars, trash cans, bicycles, or even a broom. Even a misalignment of a few degrees will break the beam. Second, check for obstructions. Dirt, spider webs, dust, or condensation on the lens can diffuse the beam. Also look for any boxes or tools sitting between the sensors. Third, direct sunlight is a major cause. If late afternoon sun shines directly into the receiving lens, it can overpower the infrared signal and cause blinking only at certain times of day. Try swapping the sensors or shielding the lens with a small piece of cardboard to test. Finally, loose wiring or a loose bracket that vibrates when the door moves can cause intermittent blinking that comes and goes.