The garage door goes down, then reverses back up

Who they are

Greg is a retired teacher who closes up the house every night before bed, garage door last.

Their home and door

A two-car garage with a belt-drive opener and safety sensors near the floor on each side of the door.

What went wrong

One night the door started down, stopped, and went straight back up, and the light on the opener kept blinking. It did the same thing every time he tried.

What they searched

• “how to fix garage door sensor”
• “green light on garage door sensor not on”
• “garage door not closing”

What they learned

• The photo-eye sensors send a beam across the opening. If anything interrupts it, the door will not close. Source: Why won’t my garage door close?
• A solid sensor light means the beam is aligned. A blinking light almost always means the sensors are out of alignment. Source: Why your garage door won’t close and the opener light keeps blinking
• Wiping the lenses with a soft, dry cloth is the most common fix on the whole door, and most openers will close if you hold the wall button down for the full travel. Source: Why your garage door won’t close and the opener light keeps blinking