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Brian, Architect
Category: Home Improvement
Satisfied Customers: 3123
Experience:  Licensed Architect- 17 years, L.E.E.D. AP
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have a liftmaster pro, the light blinks but it will not operate

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have a liftmaster pro, the light blinks but it will not operate except to make buzzing sounf
Hi and thanks for using our service! My name is XXXXX XXXXX I will do whatever I possibly can to give you the most accurate answer.

Is there a number pattern to the blinking light?
Customer: replied 3 years ago.

when you try to use the device it buzzs and blinks about 6 times

Customer: replied 3 years ago.

then stays on the normal time, then goes off

Customer: replied 3 years ago.

it actually blinks ten times, then the light stays on as normal

the pattern is usually a certain amount of blinks such as 10, then pause, 10 more blinks, pause, etc. Is this happening?
Customer: replied 3 years ago.

no, it blinks 10 times then stops

Ok....that doesn't sound like a diagnostic flash then.

The humming/ buzzing noise typically means that you need a new start capacitor inside the motor unit. It is probably starting to go. It can also be that the plastic gears are stripped or binding.

You will need to unplug and remove the cover off the motor unit to inspect the gears. You can also inspect the cylinder shaped capacitor to see if it is bulging or leaking fluid.

Another possible cause for the buzzing noise, but rare, can be that the opener may be trying too hard to open the door either because the spring(s) is weak or broken or the tracks/ rollers are bent or need lubricating.

The opener does not do the heavy lifting of the door, the spring(s) does all the work, the opener just aids in moving the door open. I would verify that the cables to the springs are still on the pulleys (if you have this type). I would also verify that the door is not going up slightly crooked, just enough to bind.

You can perform the following tests:

First, I would close the door and then disconnect the door from the trolley and operate the door manually. The door NEEDS to roll smoothly and not bind on anything and it NEEDS to be balanced and stay at any point you stop it. If the door wants to go down by itself the springs are weak/ broken and at fault; have a qualified service technician fix/ adjust them...they can be very dangerous to work with since they are under extreme tension.

Second, operate the opener without the door attached and see if it operates correctly. The trolley will fully go up and down if working properly.

Performing these tests will help narrow down whether the door/ tracks are the problem or the motor unit is giving you the problem. But my gut feeling is you need a new start capacitor.
Customer: replied 3 years ago.

the chain will not budge even with the door released from it

Customer: replied 3 years ago.

should the electric eyes have a red and green light on them. I don't see where they could be on these

I would definitely take the cover off the motor unit and see if anything is binding the gears. When the start capacitor goes the motor unit makes a buzzing noise.

I don't know the exact model number of your opener but typically the sensors have lights lit when they are aligned. Not seeing them lit on them could be a separate issue but it wouldn't cause the buzzing. In addition, if the sensors were the only problem, you would still be able to open the door normally and to close the door you would have have to hold the wall button until the door closed.
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