Sometimes the sensors will be in alignment and just as the door gets close to being shut it will vibrate enough to push one sensor off.
Residential garage door goes down but goes back up unexpectedly.
In cases like this your travel down setting simply needs to be adjusted to the new distance.
Your garage door sensor works by having two photo sensitive devices on either side of the garage door.
Because a garage door opener is a complicated creature there s a lot that can possibly go wrong.
Garage doors have many parts that all work together including safety features.
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Not only are there many different types of garage doors and garage door openers but these are actually very complicated devices despite its name your garage door opener is actually a series of different systems connected together.
When a garage door descends on command but then immediately reverses itself the problem is usually with the sensor eyes along the side tracks or with the door s wheels binding in their tracks.
But changes in weather conditions can causes your garage door components to shift or contract.
But when the door begins to descend all on its own the problem may point to the opener s logic board or the circuitry inside the motor unit itself.
Your limit switch needs to be adjusted.
You push the button to close the garage door.
A careless or rushed parking job can cause the car s bumper to block the sensor.
It goes partway down reverses direction and goes back up again.
When that happens the distance your garage door needs to travel may change.
If the door goes up seemingly on its own after you close the door be sure to check for any debris the sensor is picking up.