If your garage door opens normally but refuses to close on sunny days, the likely cause is sunlight shining straight into one of the safety sensors near the floor. The opener reads that as something blocking the doorway and will not close. The fix is to keep direct sun out of the receiving sensor: shade it, swap the two sensors to opposite sides, or add the manufacturer’s sun shield.
Why sunlight stops the door from closing
The two small sensors at the bottom of the door opening talk to each other with a beam of infrared light. One sends the beam and the other receives it. Genie explains that sunlight carries infrared light too, so when the sun shines directly into the receiving sensor it can drown out the beam. Chamberlain describes the same thing: sun in the receiving sensor blocks the light from the sending sensor, and the opener acts as if the sensors are blocked.
On Chamberlain and LiftMaster openers the receiving sensor has a green light and the sending sensor has an amber light. On Genie openers the receiving sensor is also green and the sending sensor is red. The green one is the sensor that needs to be out of the sun.
How to tell it is the sun and not something else
- The door opens fine but will not close, or starts down and goes back up, and it happens when the sun is low enough to shine into the sensor, usually early morning or late afternoon.
- The door closes normally at night or on cloudy days.
- On older Chamberlain and LiftMaster openers the opener lights also blink 10 times. Chamberlain says openers and replacement logic boards made since early 2022 no longer do that (one of its articles gives February 3, 2022, another says after 2022), so do not rely on the blinking.
If the door will not close at any time of day, check the basics first. Chamberlain’s alignment guide says both sensor lights should be on steadily when the sensors are aligned, and a blinking green light means they are out of alignment. Wipe the lenses, clear anything out of the beam, and see Chamberlain’s alignment steps.
Sun on the sensors does not make a door open by itself. If your door opens when nobody pressed a button, look at remotes, the wall control and wiring, not the sun.
Closing the door right now
On most openers you can still close the door by pressing and holding the wall button until the door is fully down. While you hold the button, the safety sensors are not stopping the door. First make sure nobody and nothing is in the doorway, keep children and pets away, and keep the door in sight until it has closed completely, as DASMA’s safety guide says. Treat this as a temporary measure until the sensor problem is fixed. Check your opener’s manual if the wall button does not work this way.
Fixes, from easiest to most involved
- Shade the receiving sensor. Genie suggests building a small box around the green sensor’s lens or taping a piece of cardboard above it, without covering the lens itself. It costs nothing, takes a few minutes and tells you right away whether the sun was the problem.
- Fit the manufacturer’s sun shield. For Chamberlain and LiftMaster sensors there is a sun blocker kit, part number 041B0873 (also listed as 41B873). Chamberlain says to check your opener’s manual for compatibility before ordering. See Chamberlain’s part page.
- Swap the sensors to opposite sides. This moves the receiving sensor to the side the sun does not reach. Chamberlain’s steps, in short: disconnect power to the opener; cut each sensor’s wire about 6 to 12 inches back from the sensor (or, if the sensors are already spliced into existing wire, undo that splice); remove the wing nuts and move each sensor to the other side of the door; rejoin the wires, white to white and the black-and-white wire to the black-and-white wire; restore power, confirm both sensor lights are on, and realign if needed. This means cutting and splicing low-voltage wire, so if you are not comfortable with that, a technician can do it for you. Chamberlain notes that after a swap the sun may reach the receiving sensor at the other end of the day, which is when the sun shield is the answer.
- Move the sensors back from the opening (Genie). Genie says its sensors can be mounted farther back from the door opening to get out of the sun, as long as they stay aligned, no farther off the wall and no more than 6 inches above the floor. Genie also says its newer Safe-T-Beam sensors have a lens designed to resist sunlight interference.
What not to do
- Do not disconnect, bypass or tape the sensors together. They are there to stop the door from closing on a person, a pet or a car.
- Do not raise the sensors to get them out of the sun. Chamberlain and Genie both say no higher than 6 inches above the floor.
- Do not cover the lens itself. Shade goes above and around the sensor, not over it.
- Skip tinted films and filters over the lens. Genie’s guidance is to shade the sensor without blocking the lens, and neither manufacturer suggests filters.
Test the sensors after any change
- With the door fully open, place an object (never a person or any part of your body) in the path of the beam so the light on the receiving sensor goes out or starts blinking.
- Press the remote to close the door. The door should not close: it may move a few inches and reverse, or stay where it is. Light and sound signals vary by model; check your opener’s manual for the expected indication.
- Remove the object and run the reversal test: lay a 2×4 flat on the floor under the door and close it. The door must reverse when it touches the board.
If the door closes with the beam blocked, or does not reverse on the board, stop using the opener to close it and call a technician. Chamberlain says the safety reversal system should be tested every month.
Quick answers
Why does my garage door close at night but not during the day? Because the sun only reaches the receiving sensor at certain times. At night there is nothing competing with the sensor’s own infrared beam.
Why does the door close when I hold the wall button? Pressing and holding the wall button overrides the safety sensors, so the door closes even though they cannot see each other. Because the sensors are not protecting the doorway while you do it, check that the opening is clear and watch the door all the way down. It is a temporary measure, not a fix.
Which sensor should be in the shade? The receiving sensor, the one with the green light on Chamberlain, LiftMaster and Genie openers.
Need a hand in Madison, Milwaukee or Rockford?
If the door still will not close after shading or swapping the sensors, or a sensor light will not stay on, call the team that serves your area: Madison (608) 420-2377, Milwaukee (414) 800-9271 or Rockford (815) 800-2025. Twins offers a $0 service call with repair.
Manufacturer and industry sources
- Chamberlain Group: sunlight interference with safety sensors
- Chamberlain: safety sensor sun blocker kit 041B0873
- Chamberlain Group: align the safety reversing sensors
- Chamberlain Group: opener light blinks but the door will not close
- Chamberlain Group: what the opener’s flashing diagnostic light means
- Chamberlain Group: test the Protector System safety sensors
- Chamberlain Group: test the safety reversal system
- Genie: Safe-T-Beam sunlight interference solutions
- DASMA: automatic garage door opener safety and maintenance guide
