Question about liftmaster Chamberlain Garage Door Opener Transmitter 300MC

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Garage door won't close without hold down the remote. Lights blink fast and I have cleaned the sensors adjusted sensors. What else can I do?

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IF THE DOOR CLOSES FULLY WHEN YOU HOLD DOWN THE WALL BUTTON AND NOT IF YOU PRESS AND RELEASE THIS DEFINATLY MEANS THE EYES ARE THE PROBLEM.

BE SURE THE SENSORS ARE MOUNTED 5" ABOVE THE FLOOR ON EITHER SIDE OF THE DOOR. ANYPLACE ELSE IS UNACCEPTABLE.

THE LIGHTS ON THE SENSORS SHOULD BOTH BE LIT AND SOLID.

WATCH THE SENSOR LIGHTS ON THE WAY DOWN IF THEY FLICKER OR GO OFF YOU HAVE AN ALIGNMENT PROBLEM.

BE SURE TO CHECK POLARITY AND CONNECTIONS ON BOTH SENSORS.

YOU CAN TAKE WIRE AND RUN IT DIRRECT TO EACH SENSOR IF YOU THINK TH PROBLEM MAY BE A BAD WIRE.

HOPE THIS HELPS

Posted on May 26, 2010

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My garage door starts down then goes back and the motor light flashes 10 times. The owner's manual only refers up to 6 flashes.


Richard, what is the make of your GD Opener unit? However, make sure the antena wire on the unit is turned up. 2. sometimes direct sun on the sensors prevent operation from the remote. 3.adjust sensors on both sides making sure the green or red lights are on.4. check the remote battery ensuring red light works when you press the remote button. 5. finally, has on vacation switch on the unit has not been switched on. GL

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I have a Sears craftsman model 139.53637SRT garage door opener. My remote has not worked in a long time. I use the wall control button and have to hold the button in order to open or close the garage door....


It sounds like your door sensors may be bad or misaligned. Make sure the small light on each sensor is lit and not flickering. That could be the cause of your having to hold the wall button down until the door is closed. You can buy a universal remote but if you only had one remote before it could be the receiver that has quit. A new remote would not fix that but the only way to find out is to try.

Aug 15, 2011 | Sears Craftsman LiftMaster Chamberlain...

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I have a liftmaster Model 1240. Door will open by remote or wall opener. The door will only close while holding wall opener button down. If i try and close via remote, light starts blinking and door...


The only thing that will cause the main light to flash 10 times and the door to reverse to the open position is a sensor problem. Make sure the light on each sensor is on and not flickering ever so slightly. Make sure they are not moving when the door starts to close. Lights on sensors should not blink. One light should stay on constantly and the other sensors light should go off when you block the sensors.

Jan 22, 2011 | Sears Craftsman LiftMaster Chamberlain...

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I can open my garage door with the remote just fine but it will not close the door. I have to go inside and hold the button down until it has completely gone down or it will come back up. i can press the...


Make sure the door sensors are pointed at one another and the small light on each one is lit and not blinking. Tweak them a bit. If you cannot get both lights to come on you have bad sensors.

Sep 12, 2010 | Sears Craftsman LiftMaster Chamberlain...

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Sensor problem with garage door opener. One of them has a yellow light the other a green. The door starts to close than stops. You can close it if you hold the button down inside and the remothe doesn't...


If it moves 6-8 inches and then stops it is most likely the rpm sensor.

Yellow and green are what the lights should be.

Does the led on the wall control blink?? If is does press the lock button.
If it doesn't you will need to reprogram the remote.

Watch the eyes as the door closes, does one of them go off? If so the track may be flexing causing misalignment. (Widen the track near the bottom)

If all of the above don't help check the sensitivity adjustment. Turn it about 1/8 turn clockwise and try the door again - continue this until the door goes full cycle without reversing. If you have to set the sensitivity past 3/4 the door needs to be adjusted.

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I have a craftsman garage door opener and I have to hold the button down in order to close the door. The door opens fine and the sensors are clear. The unit starts to close then stops, the lights start...


When you can close the door by holding down the wall button it IS the safety eyes or wiring.

If the eyes are mounted to the track. Many times the track wll move as the door closes causing the eyes to move out of alignment.
Watch as the door moves down and see if they need to be adjusted.

If the eyes are not both lit - they are out of alignemnt or have a wiring problem. try adjusting them and see if the lights come on. - if not check the wiring

Hope this helps

Jul 12, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Both lights on our garage door sensors are green (not blinking), but the door will not close with the remote or button in the garage. It does close if you force it by holding down the button in the garage....


If the main light flashes 10 times when the door starts to close and then reverses it is a door sensor problem. Look very closely at the lights on the sensors. If one of them is flickering ever so slightly it will give you the problem you have.

If the main light is not flashing then you need to increase the down force which is near where all those white wires go. A 1/4 turn should do it.

Nov 29, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

When try to use remotes or wall control to close garage door, lights blink 8 times. Can only close by holding down wall control the entire way.


Your door sensors are most likely misaligned. Each of them should have a small light that is lit and not blinking. Tweak them until both are lit.

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