There is a specific, sinking feeling that every homeowner knows: you press the button to close your garage door, watch it descend a few inches, and then immediately reverse back up, accompanied by the frantic clicking of the opener lights. You try again. Same result. You hold the wall button down, and it forces the door closed, but the moment you release it, the door reverses.
You are likely dealing with a failure of the garage door safety sensors (also known as "photo-eyes"). These small black boxes located at the base of your tracks are the most common cause of a "door that opens but won't close." While they are small, they hold veto power over your entire garage door system. If they are misaligned, dirty, or malfunctioning, your opener is legally and mechanically required to refuse to close the door.
In Dahlgren, VA, sensor issues are frequent due to our specific environmental factors—intense sunlight blinding the sensors, humidity corroding the delicate low-voltage wiring, and shifting foundations knocking them out of alignment. At Ace, we treat sensor repair not as a nuisance, but as a critical safety restoration. We don't just bypass the problem; we diagnose exactly why the beam is breaking and restore the "invisible wall" that protects your family, pets, and vehicles from the crushing force of a closing door. Call (888) 670-9331.
Sensors have a very limited vocabulary. They can only tell the opener "Yes" (safe to close) or "No" (unsafe to close). However, the way they deliver this message provides crucial clues to the technician about what is actually wrong.
This is the classic presentation. The door opens perfectly fine because sensors are ignored during the opening cycle (safety is only a concern when the door is coming down). However, when you try to close it, the door acts as if it has hit a brick wall before it even moves. This confirms that the opener believes there is an obstruction, even if the opening is clearly empty.
Sometimes the door will travel six inches or a foot before reversing. This suggests an intermittent signal break. The vibration of the door moving might be shaking a loose sensor wire or rattling a misaligned bracket just enough to break the beam for a millisecond. That millisecond is all the opener needs to trigger the safety reversal.
Garage door sensors come in pairs: a Sender (amber light) and a Receiver (green light). If the Amber light is off, the system has no power or a broken wire. If the Green light is blinking or off (while the amber is on), the sensors have power but are misaligned. The receiver cannot "see" the sender's beam. If the Green light is flickering, the alignment is on the edge—vibration will likely break it.
If both little LED lights are dark, the issue is rarely alignment. It is usually a wiring fault. The low-voltage "bell wire" that connects the sensors to the motor head may have been cut by a weed whacker, chewed by a rodent, or disconnected at the terminal screws on the opener itself.
Modern openers are smart. When they reverse the door, they will flash the main overhead light bulb a specific number of times to tell you why. LiftMaster/Chamberlain: Typically flashes 10 times rapidly if the sensors are misaligned or obstructed. Genie: Uses red/green LEDs on the powerhead to indicate sensor status. Knowing this code helps Ace technicians verify the diagnosis before opening the toolbox.
This is the "override" feature. By holding the wall button down, you are telling the opener, "I am watching the door, and it is safe to close; ignore the sensors." If the door closes only when you hold the button but reverses when you use the remote, you have a confirmed sensor failure. Remotes cannot override the safety system; only the hardwired wall button can.
This is the most frustrating scenario. The door works fine in the morning but fails in the afternoon. This is often a sign of Sun Interference (the sun blinding the receiver at a specific angle) or a wire with a tiny break inside the insulation that only separates when the temperature changes.
To understand the repair, it helps to understand the technology. It is a simple but precise system.
The system consists of two units mounted 6 inches off the floor on either side of the door. The Sender (Emitter): Sends a continuous, invisible beam of infrared light across the opening. The Receiver (Detector): Looks for that light. As long as it "sees" the beam, it completes a low-voltage circuit that signals the opener "All Clear."
You cannot see the beam with the naked eye. It is a focused cone of infrared energy. Alignment is critical because the beam spreads slightly over distance, but the receiver's "eye" is very small (about the size of a dime). If the sender is pointed even a few degrees off-center, the beam will miss the receiver entirely over the 16-foot span of a double garage door.
If a child, a pet, a bicycle tire, or a car bumper breaks the beam, the receiver stops sending the "All Clear" signal. The opener's logic board registers this interruption instantly (within milliseconds) and triggers the reversal protocol. The door stops and goes back up to prevent crushing the object.
If the sensor breaks internally, it fails "safe." This means if the sensor dies, the opener defaults to the assumption that there is an obstruction. It will not allow the door to close. This "fail-safe" design ensures that a broken sensor doesn't leave you with a dangerous, unmonitored door.
We often hear, "But it opens fine! Why won't it close?" The answer is gravity. An opening door is moving away from the floor; it cannot crush anything against the concrete. A closing door is a crushing hazard. Therefore, the safety sensors are only active and monitored during the down cycle.
This isn't just a manufacturer feature; it is federal law (UL 325 standard). Since 1993, every residential garage door opener manufactured for use in the US must have a non-contact safety reversal system. You cannot legally remove them. Ace will not service an opener if the sensors have been removed or bypassed, as it places unlimited liability on the homeowner and the technician.
Alignment, wiring, replacement — same-day service, flat-rate pricing.
Call (888) 670-9331While the technology is universal, the failure modes are often local. Dahlgren, VA presents a unique set of challenges for these delicate electronic components.
This is the #1 cause. Sensors are mounted on thin aluminum brackets near the floor. A garbage can bumping them, a broom sweeping past, or even the vibration of the door tracks can knock them out of alignment. If the "eye" is pointed 2 degrees to the left, the beam misses the receiver, and the door won't close.
Garages are dusty places. Over time, a layer of dust, pollen, or spiderwebs can accumulate on the glass lens of the sensor. This acts like a fog, scattering the infrared beam until it is too weak for the receiver to detect. In Dahlgren, VA, where pollen counts can be high, this "blindness" is a common seasonal issue.
The sun emits massive amounts of infrared radiation. If the sun is low in the sky (morning or late afternoon) and shines directly into the lens of the Receiver sensor, it "washes out" the infrared signal from the sender. The receiver is blinded by the glare and cannot see the beam. The opener interprets this blindness as an obstruction. This is why your door might work fine at night but fail at 5:00 PM.
The wires running from the sensors to the ceiling are thin (22-gauge). They are easily damaged by weed trimmers near the garage opening, staples that were driven too tight during installation, or rodents chewing on the insulation. If the copper wire inside breaks, the signal stops.
In Dahlgren's humid climate, moisture can wick into the wire nuts or splice connectors used to join the sensor wires. This causes the copper to oxidize (turn green/black), creating high electrical resistance. Eventually, the voltage drop is too great, and the sensor powers down.
Electronics don't last forever. The soldering on the internal circuit boards can crack from years of vibration. The LED emitter can grow dim. If your sensors are 15+ years old, they may simply be too weak to push the signal across a 16-foot opening reliably.
Lightning strikes or grid surges can travel down the low-voltage wiring and fry the sensor chipsets. Often, the opener survives, but the sensitive sensors are destroyed.
If a bicycle falls over or a car tire bumps the track, the sensor bracket can be crushed. We often see sensors that are literally hanging by their wires, pointing at the floor.
Like any light bulb, the infrared LED in the sender can fade over time. It might still be "on," but the beam is too weak to trigger the receiver, especially on wide double-car doors.
Just because the door reverses doesn't mean the sensors are broken. Other problems can mimic sensor failure. Ace technicians are trained to tell the difference.
If the door hits a snag in the track (a physical bind), the opener's Force Sensor detects the resistance. It assumes the door has hit a car and reverses. This looks exactly like a sensor reversal, but the lights usually won't flash the "sensor code." If we adjust the sensors and the door still reverses, we check the force settings.
If the tracks are misaligned or a roller is seized, the door requires more force to close. If that force exceeds the safety limit, the door reverses. This is a mechanical safety reversal, not an electronic sensor reversal.
If the "Down Limit" is set too far, the opener tries to push the door through the concrete floor. When it can't, it assumes an obstruction and reverses. This happens after the door touches the floor, whereas sensor reversals happen before or during travel.
Sometimes the sensors are fine, but the "brain" (logic board) that reads them is fried. The board might be permanently stuck in "obstruction mode" even if the sensors are sending a clear signal.
We see homeowners replace sensors three times, only to find out the problem was a loose track bolt. Ace diagnoses the whole system to ensure we are fixing the actual cause of the reversal.
Don't replace sensors three times when the problem is elsewhere.
Call (888) 670-9331We don't just "wiggle them until they work." We perform permanent repairs.
We use laser levels or string lines to ensure the sender and receiver are perfectly parallel. We tighten the wing nuts on the brackets to lock them into this perfect alignment so they don't drift again next week.
We clean the lenses with non-abrasive electronics cleaner to remove the "fog." We check the door tracks for spiderwebs, leaves, or hanging wires that might be momentarily breaking the beam.
If we find a cut or corroded wire, we strip it back to clean copper and use gel-filled, waterproof connectors to create a permanent splice. We re-route wires away from moving parts to prevent future damage.
We check the connection points at the opener head. We clean the terminals and ensure the wires are seated firmly.
If a sensor is dead, we replace the pair. (It is rarely cost-effective to replace just one, as they are sold in kits). We install new brackets and splice the new sensors into the existing wiring if the wiring is sound.
If the brackets are bent or rusted, sensors will never hold alignment. We install new, heavy-duty steel brackets. In some cases, we move the sensors from the tracks to the wall (using "clip-on" vs. "floor mount" brackets) to protect them from impact.
For homes facing East or West in Dahlgren, VA, we install "sun shields" (small cardboard or plastic tubes) over the receiver lens. This acts like a baseball cap, blocking the peripheral sunlight while allowing the focused infrared beam to enter.
If sensors are constantly getting wet or hit, we can sometimes relocate them slightly higher (though they must remain within 6 inches of the floor by law) or move them further back into the garage to protect them.
If the wiring inside the wall is shorted (stapled through), we run brand new low-voltage wire from the opener to the sensors, stapled neatly and safely.
We are strict about sensors because they save lives.
Before 1993, children were frequently injured or killed by closing garage doors. The sensors are the primary defense against entrapment. They detect a toddler or a pet that is too small to be seen from the driver's seat.
A garage door can exert 150+ pounds of crushing force before the mechanical force settings trigger a reversal. That is enough to break bones or damage a vehicle. The sensors prevent the door from even touching the object.
Kids run fast. A dog chases a ball. The sensors react in milliseconds—faster than you can hit the stop button on the remote.
We often see sensors taped together and thrown on top of the opener motor to "trick" the system. This is incredibly dangerous. It removes the protection entirely. Ace technicians are trained to disable any system found in this state until it can be repaired properly.
The Box Test: Open the door fully. Place a cardboard box (at least 6 inches tall) in the path of the door. Press the close button. The door should start down, "see" the box, and reverse immediately. It should not touch the box. If the door hits the box, call Ace immediately.
Same-day repair. Proper alignment. Verified function.
Call (888) 670-9331We check the LEDs. Are they solid? Blinking? Off? This tells us 90% of the story.
We wiggle the sensors to see if the connection is loose. We adjust the angle to see if we can get a solid green light.
We trace the wire path. We look for staples that are too tight, cuts, or corrosion at the wire nuts.
We rule out force settings, track binding, and logic board failure.
We perform the fix. We use waterproof connectors and secure mountings.
We close the door to ensure it runs smooth. Then we break the beam with our foot or a box to ensure it reverses instantly.
Sensors are not universal. You cannot put Genie sensors on a LiftMaster opener.
These are the most common. They use a proprietary "pulsed" signal. Older units had green/orange lights; newer ones have green/amber. Ace stocks OEM replacements.
Genie uses a different technology (Safe-T-Beam). They have specific red and green diagnostic LEDs that pulse to indicate system health.
We carry sensors for Linear, Wayne Dalton, and Stanley openers.
For some older or off-brand openers, we can use universal sensor kits that are compatible with multiple protocols.
If your sensors are the old "through-beam" style that are prone to failure, we can upgrade you to modern, interference-resistant sensors.
OEM sensors on the truck. Fixed in one visit.
Call (888) 670-9331Repairing sensors is generally one of the most affordable garage door repairs.
Wiring complexity (is the wire hidden in the wall?), sensor brand, and whether it's a repair vs. replacement.
| Service | Typical Range |
|---|---|
| Sensor Realignment & Cleaning | $80 — $150 |
| Sensor Wire Repair / Splice | $100 — $175 |
| Sensor Replacement (pair + install) | $150 — $250 |
| Full Wiring Run Replacement | $200 — $300+ |
The cost of holding the wall button every morning is frustration. The cost of a door closing on a car bumper is $500+. The cost of a safety incident is incalculable. Sensor repair is cheap insurance. Call (888) 670-9331.
We don't just sell you parts. We make sure the repair fixes the problem — sensors vs. everything else that mimics sensor failure.
We carry LiftMaster, Genie, and universal sensors on the truck. We fix it in one visit.
We know how to trace low-voltage shorts and use waterproof splices. Not just swapping the visible unit.
We know the "afternoon blindness" problem better than anyone, and we have the sun shields to fix it.
We test the "close" and the "reverse." Both tests must pass, or we don't leave.
Flat rate pricing. You know the cost before we snip a wire.
We are in your area daily, fixing the blinking lights and reversing doors.
Serving the entire region with prompt, professional sensor repair. Call (888) 670-9331.
Almost always a safety sensor issue. Sensors are only active during the closing cycle. If misaligned, dirty, or malfunctioning, the opener refuses to close. Try holding the wall button — if it closes, sensors are confirmed.
Realignment/cleaning: $80-$150. Wire repair: $100-$175. Sensor replacement (pair): $150-$250. Full wiring run: $200-$300+. One of the most affordable garage door repairs.
Usually sun interference (afternoon sunlight blinding the receiver) or a wire with a tiny break that separates when temperature changes. Ace installs sun shields and uses waterproof connectors.
Never. Federal law (UL 325) requires sensors on all residential openers since 1993. Bypassing removes protection against entrapment. Ace will not service systems with sensors removed or bypassed.
Green light blinking or off (amber steady): sensors have power but are misaligned. Both lights off: wiring fault. Amber off: no power. The LED pattern is the first diagnostic clue.
Yes. The sun emits infrared radiation that can "wash out" the sensor beam. Common in east/west-facing garages at sunrise/sunset. Ace installs sun shields to block peripheral sunlight.
The Box Test: Place a 6-inch tall cardboard box in the door path. Press close. The door should reverse before touching the box. If it hits the box, call Ace immediately.
No. LiftMaster, Genie, and other brands use proprietary signals. You can't put Genie sensors on a LiftMaster. Ace stocks OEM replacements and universal kits for older/off-brand openers.
Don't hold the button down for another day. Stop the blinking and the frustration. The experts at Ace are ready to align, repair, or replace your sensors so your door closes safely and automatically every time.
Call (888) 670-9331 today for same-day sensor repair.