Safety sensors send an invisible beam across the door. If direct sun hits the receiving sensor, the opener can read the beam as broken and reverse the door. Look at the two small lights, clean the lenses and check nothing blocks the beam. Never bypass the sensors. A technician can fix the sun problem for good.
How the sensors work
Two small sensors sit near the floor, one on each side of the door. Chamberlain's manual says the sending eye, with an amber light, transmits an invisible beam to the receiving eye, with a green light. If something breaks the beam while the door is closing, the door stops and reverses to fully open, and the opener lights flash 10 times.
The sensors must face each other. The same manuals say the beam must be no higher than 6 inches (15 cm) above the floor. They also warn not to let direct sunlight reach the receiving eye, because sun can swamp the beam in the same way an object does.
Why afternoon sun causes trouble
The sun's angle changes through the day and through the seasons. For part of the day, light may shine straight into the lens of the receiving sensor on one side of the door. The opener then thinks the path is blocked. Chamberlain's manuals say the units can go on either side of the door only as long as the sun never shines directly into the receiving eye lens.
That is why the problem often shows up at the same hour each day and disappears in the evening. It may also start when a tree is trimmed or the seasons change the light.
What you see and what it likely means
| What you see | What it likely means | What to do |
|---|---|---|
| Door reverses only at one time of day, lights flash | Sun on the receiving sensor | Do the checks below, then ask a technician to move or shade it |
| Door reverses at any hour, lights flash | Beam blocked or sensors knocked out of line | Clear the path and look at both lights |
| One sensor light is off | No power or a wiring fault at that sensor | Call a technician |
| Lights look normal but the door still stops | Another fault, such as travel limits or door balance | Stop using the opener and call |
Sensors are the first thing to check, not the only thing.
Four checks you can do
Note the time
Write down when the door reverses and which side of the house the sun is on.
Look at the two lights
With the door open, the amber light and the green light should both stay on. If the green light dims or goes out only when sun hits it, sun is the likely cause.
Wipe the lenses
Use a soft, dry cloth. Dust and cobwebs can also weaken the beam.
Clear the beam
Move boxes, cords, tools and leaves away from the path. Do not bend or pull the sensors out of line.
The sensors exist to stop a closing door from hitting a child, a pet or a car. Do not tape them, disconnect them or hold the button to force the door down. If the door will not close, leave it open and call. Do not adjust springs or cables either. See garage door repair.
Quick answers
Why does my garage door reverse only in the afternoon?
Direct sun may be shining into the lens of the receiving sensor. The opener reads the weakened beam as a blocked path and reverses the door.
Which sensor is affected by sunlight?
Chamberlain's manual warns against direct sunlight on the receiving sensor, the one with the green light. The sending sensor has an amber light.
How high should garage door sensors be?
Chamberlain's manual says the beam should be no higher than 6 inches (15 cm) above the floor, and the two lenses must face each other.
Can I disable the sensors to close the door?
No. They are a safety device. If the door will not close, leave it open and have a technician fix the cause.
What a technician can do
The fix depends on your opener and your layout. Options include moving the sending and receiving sensors so that the green receiver sits on the shaded side, aiming them again, shading the receiver, or fitting newer sensors made to handle bright light. A technician also checks the wiring, the door balance and the opener settings so the sun is not hiding a second fault.
Sensors, rollers and tune-up work fall in an approved range of $150 to $350, and we confirm the final price after we see the door. See opener repair and what each fix costs in Texas.
Who to call
Emil Garage Doors repairs garage doors, springs, cables and openers and installs new doors in Texas, including Georgetown, Round Rock and Austin. Call or send your details with the time of day it happens and we book the soonest visit.
Related services
Need help near you?
We repair and install in these cities. Each page has local notes, prices and reviews.