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Every September, Calgary homeowners experience a puzzling phenomenon: garage doors that worked perfectly all summer suddenly refuse to close. The door goes down, reverses, and the opener light blinks—with no visible obstruction. By November, the problem vanishes as mysteriously as it appeared.
This isn’t a malfunction. It’s physics.
At Calgary Garage Door Fix, we’ve documented a consistent pattern over years of service calls: sensor-related issues spike during specific windows each year—late February through April, and again from mid-September through October.
One service note from our records captures the phenomenon perfectly:
“The customer is experiencing intermittent sensor issues only at certain times of day, and it appears to recur every year.”
— Technician note, September 2025
The customer’s garage door had worked flawlessly during the year. Nothing had changed—except the calendar. As fall approached, the sun’s angle shifted just enough to blast directly into her garage opening at sensor height during morning hours.
If your garage door closes normally at night or on cloudy days but fails during sunny mornings, sunlight is almost certainly overwhelming your safety sensors. Try shading the sensor with your hand—if the door closes immediately, you’ve confirmed the diagnosis.
Garage door safety sensors use infrared (IR) light beams—the same type of radiation that makes up a significant portion of sunlight. The sun’s IR output is thousands of times more intense than your sensor’s weak beam. When direct sunlight hits the receiving sensor, it’s like trying to hear a whisper next to a jet engine.
The key factor is **solar declination**—the angle between the sun and Earth’s equatorial plane. This angle changes throughout the year due to Earth’s 23.44° axial tilt, which directly determines how high the sun climbs in Calgary’s sky.
| Season | Date | Noon Sun Elevation | 8 AM Sun Elevation |
|---|---|---|---|
| Summer Solstice | June 21 | 62.4° | 32-34° |
| Fall Equinox | September 22 | 39.0° | 8-10° |
| Winter Solstice | December 21 | 15.6° | Below horizon |
| Spring Equinox | March 20 | 39.0° | 8-10° |
During summer, even the early morning sun climbs quickly above garage door openings. But during the equinoxes, the sun rises almost exactly due east and stays at low angles (8-10°) during the 7-9 AM window when most Calgarians leave for work—a perfect trajectory to shine directly into east-facing garage door openings at sensor height.
Calgary sits at 51.05°N latitude—significantly farther north than most major North American cities. This northern position amplifies the seasonal sun angle variation compared to locations closer to the equator.
– Sunrise shifts from 7:05 AM to 7:52 AM
– Sun rises almost due east (85-95° azimuth) – 8 AM elevation drops from 15° to 8°
– East-facing garages experience peak interference
– Sunrise shifts from 7:15 AM to 7:30 AM (DST change)
– Sun again rises due east
– Morning angles mirror fall conditions
– Second annual peak in sensor issues
– June sunrise at 5:21 AM means sun is already 20°+ by 7 AM
– High angles pass over garage openings
– Sunlight enters at ceiling level, not sensor level
– December sunrise at 8:37 AM—most departures happen in darkness
– When sun does rise, it’s in the southeast (125-135° azimuth)
– Only southeast-facing garages affected
Not every Calgary home experiences sun-blinded sensors. The key variable is which direction your garage door faces.
| Orientation | Risk Level | Notes |
|---|---|---|
| East-Facing Garages | HIGH RISK | Peak problem period: 7-9 AM during equinoxes The sun rises in the east and shines directly into the opening during morning departure times. This is the most commonly affected orientation. |
| West-Facing Garages | MODERATE RISK | Peak problem period: 5-7 PM during equinoxes Afternoon sun can blind sensors during evening arrivals. Less commonly reported because homeowners often close the door from inside. |
| Southeast-Facing Garages | MODERATE RISK | Peak problem period: 8-10 AM during winter months The winter sun rises in the southeast, potentially affecting these orientations when equinox-affected homes get relief. |
| North-Facing Garages | LOW RISK | Direct sunlight rarely enters north-facing openings in the Northern Hemisphere. These homes typically don’t experience sun interference. |
| South-Facing Garages | LOW RISK | While south-facing garages receive abundant sunlight, it enters at high angles that pass over the low-mounted sensors. |
Major garage door opener manufacturers explicitly acknowledge sun interference as a known phenomenon, not a warranty issue or equipment defect.
Genie Company published official documentation stating: “Sunlight carries infrared light, just like safety sensors do. This can cause an issue because the sun’s rays may interfere with the sensor’s infrared light and the sensors might not be able to signal one another.”
LiftMaster and Chamberlain sell a dedicated accessory—the Safety Sensor Sun-blocker Kit (Part #041B0873)—specifically designed to address this issue. The product description explicitly states it prevents “accidental reversal of garage door from sunlight shining directly into the safety sensors.”
The existence of commercial solutions from major manufacturers confirms this is a widespread, recognized phenomenon affecting homes across North America—not isolated incidents or defective equipment.
Based on manufacturer recommendations and field experience, here are the most effective solutions ranked by success rate and practicality:
The highest-success, zero-cost fix. Only the receiving sensor (green LED on LiftMaster/Chamberlain) is vulnerable to sunlight. The transmitter (yellow/amber LED) simply emits light and isn’t affected by incoming radiation.
Physically switch which side the transmitter and receiver occupy. Move the receiver to the shaded side of the door opening and put the transmitter on the sunny side.
Time Required: 15-20 minutes
Cost: Free
Tools Needed: Screwdriver, electrical tape, wire cutters.
LiftMaster, Chamberlain, and Genie all offer sun shield accessories that create a visor effect over the sensor lens.
– LiftMaster/Chamberlain: Part #041B0873 (~$24)
– Genie Safe-T-Beam Version 2 has built-in sun resistance
A simple, effective improvised fix:
– Use an empty toilet paper tube cut to 2-3 inches
– Or use 1-inch PVC pipe cut to similar length
– Slip over the receiving sensor
– Paint interior flat black to reduce reflections
Moving sensors 6-12 inches back from the door opening places them in the natural shade of the garage structure. Mount on the wall rather than the track if needed.
Slightly tilting the sensor downward can move the lens out of the sun’s direct path. Verify the green indicator remains solidly lit after adjustment.
While sensor position swaps resolve most sun interference cases, some situations require professional assessment:
– Wiring limitations prevent swapping sensor positions
– Sensors are physically damaged from age or impacts
– Problem persists after trying position swap and sun shields
– Opener is 15+ years old and sensors may need complete replacement
– You’re uncomfortable working with electrical components.
A professional technician can also identify whether your issue is truly sun-related or caused by other factors like wiring degradation, sensor failure, or garage door opener logic board problems. As a rule of thumb, we recommend trying to troubleshoot the sensor issue before contacting a professional garage door company, but when it comes to your garage door cables, springs, or even a proper garage door maintenance, it’s always best to call a professional.
If your garage door has started refusing to close on sunny mornings, we can diagnose whether it’s sun interference or another issue—and implement the right fix. Call Calgary Garage Door Fix and get your sensor issue resolved!
ABOUT THE AUTHOR
Stan Klugman | Founder, Calgary Garage Door Fix
Stan has over 15 years of experience in the garage door industry and has personally overseen more than 32,000 residential and commercial repairs across Calgary. Calgary Garage Door Fix is a BBB-accredited business and holds registered trademarks in both Canada (TMA1352082) and the United States (98141232).