Lift Master 3800 - Weird Issue, Not Yet Discussed

[rpuddy]

So I have had a garage door guy out about 4 times on this opener and they can't seem to fix it for the long term. The door can move and stop freely without the opener hooked up, so its unlikely a spring/cable tension issue. The door is aligned, etc.

So the issue is sometimes as I pull out of the garage, I hit the HomeLink on my car and the garage begins to go down, then come to a jolting stop about 1.5-2 feet on its way down, then cranks back up. It will do this about 3-5 times, then operate properly and lower the door to the ground.

Ideas?

 

[Chris Adams]

That's a classic description of sunlight hitting the sensor.
Got a piece of chrome, etc. on your car reflecting light into the eye?

On one of my doors you couldn't close the door at very specific times of the morning, that is, on June 1'st you could not get the door to close at exactly 6.40 in the AM. Ten minutes either way, no problem.
It was the sun hitting my neighbor's truck windshield.

I didn't figure it out, two pro's tested the door, both have installed doors for me before, and were excellent techs. The truck wasn't there, and they were not there at the right time.

I actually only figured it out by noticing the times varied with the sun rise, and later noticed if the neighbor did not park his truck in his driveway, it didn't happen.

I put a very small sun shield (thin bent tin) in just the right place and fixed the problem.

 

[carhunter]

when ours does that (different opener brand) its because the optical sensor on the bottom of the track is blocked. Often its a leaf or dust is stuck to a cobweb nearby. It may be something incredibly simple in the sensor system, if yours has it.

 

[rpuddy]

That's a classic description of sunlight hitting the sensor.
Got a piece of chrome, etc. on your car reflecting light into the eye?

On one of my doors you couldn't close the door at very specific times of the morning, that is, on June 1'st you could not get the door to close at exactly 6.40 in the AM. Ten minutes either way, no problem.
It was the sun hitting my neighbor's truck windshield.

I didn't figure it out, two pro's tested the door, both have installed doors for me before, and were excellent techs. The truck wasn't there, and they were not there at the right time.

I actually only figured it out by noticing the times varied with the sun rise, and later noticed if the neighbor did not park his truck in his driveway, it didn't happen.

I put a very small sun shield (thin bent tin) in just the right place and fixed the problem.

Interesting scenario - but it happened at night as well... could it be the nearby streetlight?! Can't be THAT sensitive... can it?

 

[darkk]

Mine (LM3800) did almost the same a couple times. It would have a jerky movement on the way down the last couple feet. Sometimes it would reverse and go all the way back up. Had to readjust the close pressure. The guy came out and held pressure against the door as it was closing so the door exerts more power to close. ??? Didn't make any sense to me (still doesn't) but it has been fine since. Go figure.

 

[rpuddy]

Mine (LM3800) did almost the same a couple times. It would have a jerky movement on the way down the last couple feet. Sometimes it would reverse and go all the way back up. Had to readjust the close pressure. The guy came out and held pressure against the door as it was closing so the door exerts more power to close. ??? Didn't make any sense to me (still doesn't) but it has been fine since. Go figure.

So as the garage was coming down, he was pushing up on the door?

 

[Chris Adams]

Interesting scenario - but it happened at night as well... could it be the nearby streetlight?! Can't be THAT sensitive... can it?

No, doesn't sound like it. The sensor picks up infra red, thus gets almost nothing at night.
Best of luck.

 

[nova65ss]

Most garage door openers are not affected by the sunlight at all.

It sounds like a photo eye issue, cable tension monitor, or maybe the sensitivity. The next time it happens you need to check and see if the service light is flashing after it returns back up, if it is it is a photo eye issue if it is not flashing then it is the monitor or the sensitivity.

 

[darkk]

So as the garage was coming down, he was pushing up on the door?

Yes, he said something about the pressure being set to about 70 pounds...no idea what he was talking about but whatever it was it worked...

 

[yucholian]

Reprogram the down pressure/position.
Also check for the lever switch that senses the cable tension, make sure it''s not loose from the wall. My money is on reprogramming.

 

[ksp]

Make sure the cable tension safety switch is not activating because of a loose cable when first starting down. Had the same issue and I ended up angling the horizontal tracks so the door had tension on it when up.

 

[darkk]

Reprogram the down pressure/position.
Also check for the lever switch that senses the cable tension, make sure it''s not loose from the wall. My money is on reprogramming.

You can circumvent the cable tension switch temporarily just to test this theory. Just put something to hold that tension switch open for testing. This way you will know if it's the cable being too loose or not.

 

[StarWolve]

http://www.garagejournal.com/forum/showthread.php?p=1557090

Same thing is happening on mine. I believe it is the tension sensor, as I can pull down on the door as it closes and it will come down, but won't do it on it's own. My door installer needs to come back out and try adjusting it again.