Question about liftmaster Chamberlain Garage Door Opener Transmitter 300MC

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Door goes up ok, but will only go down a bit then stops...

Called the repair guys, they said to check the light sensors at the bottom of the doorframe for cobwebs/dust...did that and it worked. Ran the door up and down about 5 times, worked like a charm. Then on 6th time, it stopped half way down. Called the repair guys again, they said that doors are not designed to run up and down so many times so quickly. That it has a safety mechanism that stops it before it seriously overheats. Said to wait about 30 minutes for it to cool-off/reset itself. Am now waiting 30 minutes. That make sense to you?

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What the repair guys told you is true.

Posted on Jul 13, 2009


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1 Answer

Problem with AWO3561 wash machine red door light flashing

there is a valve for the door lock if this goes it thinks the door is open and shuts down thinking the door has been opened if the feed pipe become blocked the water pressure sends air pressure to the switch when water is added. spin/drain setting it don't use this sensor switch, but on filling up it will. its usual down to a blocked pipe , or a leak in the line. sometimes it can be the switch, the pipe is located at the bottom around 2 inches from the bottom and the feed wire goes to a sensor , take the pipe off and blow down it best to have some water in the bottom of the drum, so suck and blow on the pipe to loosen anything blocking the pipe. switch don't blow or suck on this as it can damage the sensor. if the sensor is at fault you can only replace it as the valve inside for the switch if you use anything it will pierce the valve , hope this helps you.

Jun 24, 2017 | Washing Machines

1 Answer

Lift master 1/2 hp door not closing...moves a foot and then stops and goes back...eyes are good, both lights solid...have messed with the force to see if that helps...and nothing...light on opener itself...

check for a break in one of the wires that goes to the safety door stop sensors at each side of the door, the only thing that stops the door after a foot of progress is those sensors, and they can be off line quite a bit before being mis aligned , this question was listed under chain saws,, so if you could give me the make and model of your door opener I could help you more ,, just reply to this reply

Sep 08, 2011 | Garden

1 Answer

Hi I have a Chamberlain garage door system. I use the remote to shut the door. The door goes down to a foot off the ground and goes back up again. I've tried for over an hour to get it to shut and it won't...

The motor has probably been shut off by the thermal protector. Wait 15 to 20 minutes and it will reset itself.

If when the door reverses and goes back up, the main light flashes 10 times it is a door sensor problem. Make sure they are pointed at one another and the small light on each one is lit and not flickering. Tweak them a bit. If you cannot get both lights to come on you have a bad sensor.

Feb 18, 2011 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

I have a chamberlain liftmaster professional Formula 1 Garage door opener that has been working for 5 years. Now will not go down unless you hold the main button. Sensors blink when it hits within 3...

Anytime the main light flashes 10 times and the door reverses to the open position it is a door sensor problem. They each have a small light that should be lit, both should be the same brightness and not flickering ever so slightly. If not tweak them a bit. If both lights will not come on you have bad sensors.

Sep 27, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Door goes up just past eye and stops. If I hold button down will go up all the way. Must hold button down for down position also or stops every couple feet.

Check your door springs and also remove the cover and check the drive gear. It is a white nylon gear just in front of the motor and may be stripped. You need to check your door sensors also. Make sure they are pointed at one another and the small light on each one is lit and not flickering. Tweak them a bit if necessary.

Mar 08, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

I have sears opener #139.53989. Every once in a while I have a down problem. It goes down within an inch of the floor and reverses. Sometimes I can hold the wired remote button and it will go all the way...

If the main light flashes 10 times when the door reverses it is a sensor problem. Check them very closely. If they are just a little off one of them will be flickering but it is difficult to see. This can also cause the problem to be intermittent. Tweak them just a little.

It is normal for that light to blink randomly.

Jan 27, 2010 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Door hit bottom and goes back up. one sensor light is green and

your door must have a pressure switch, and it is hitting the floor before the motor stops.

with the door topped out, release the lock and push the door closer to the motor and relock.

have a helper present to be safe

Jul 03, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Door will only close when held down

sounds like the gear drive is getting worn.
also make sure the track are free of any debris.

Aug 17, 2008 | Chamberlain Powerdrive PD422D 1/2 HP...

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