Photo Eye Faults and Sensor Alignment

A door that starts down, stops, and rolls back up on an empty floor is almost always a sensor complaint rather than a motor complaint. The troubleshooting sequence at Long Beach Garage Door Service, CA 121 Melody works through it in order, because this single fault accounts for a large share of after hours garage door calls across Long Beach.

What the Pair Is Doing

Two small units face each other across the opening, roughly six inches off the slab. One sends an infrared beam, the other receives it. Break that beam while the door is travelling down and the opener reverses. The safety sensor pair has been mandatory on residential units since the early nineties, and no legitimate repair disables it.

Read the Lights First

Each unit carries an indicator. The sending side normally shows a steady light whenever it has power. The receiving side shows a steady light only when it can see its partner, and it flickers or goes dark when it cannot. A dark sending side is a power or wiring problem. A flickering receiver is a misaligned sensor or an obstruction.

The Ordinary Causes

A bike leaning against the bracket. A cobweb across the lens, which is enough at a low sun angle. A photo eye knocked out of true by a trash can. Direct afternoon sun straight into the receiving lens, which is a genuine coastal problem in west facing garages and shows up at the same time every day for a few weeks a year.

Aligning Them Properly

Loosen the wing nut, move one unit slowly until the receiving light goes solid, then tighten it without letting anything shift. Both should sit at the same height and both should be square to the opening rather than tilted. If the light only holds while you touch the mount, that mount is loose against the vertical track and needs attention first.

When It Is the Wiring

Staples driven through low voltage wire during a garage remodel are common, and the symptom is intermittent rather than constant. So is corrosion inside a wire nut in a damp corner. Repeated reversal with two solid lights points instead at the travel limit or the force setting, which is a different adjustment entirely.