Question about liftmaster Chamberlain Garage Door Opener Transmitter 300MC

1 Answer

Lift-Master GDO goes up, not down

1/2 HP Lift-Master GDO. No recent gear replacement or adjustments. Door started to fail to go down. Adjusted down sensor to max, no effect. Electric eye operation is normal. No evidence of gear shavings inside, RPM sensor seems to be working correctly. (When I disconnected it, it failed differently)
Door will come up just fine once down. Even when I disconnected trolley from door, trolley only moves about 12 inches, then reverses. LED sensor flashes 4 times. Any hints?

Posted by on

1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that gotĀ 5 achievements.

    Novelist:

    An expert who has written 50 answers of more than 400 characters.

    Governor:

    An expert whose answer gotĀ voted for 20 times.

  • Expert
  • 152 Answers

If the door operates freely without any binding, while operating it manually then It would appear that the obstruction sensor mounted across the doors path is ether out of alignment, lens dirty,or malfunctioning

Posted on Feb 22, 2009

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

My garage door does not want to close but it will open with no trouble I reset it but it still does the same thing the one I have is 1/2 HP model #139.54985 can you help me?


You need to check your sensors first. If they are lit and aligned, increase your down force. Have you recently had the springs adjusted or serviced by a garage door tech? If so, force probably needs to be adjusted and the tech failed to adjust it accordingly. If not, one of your sensors is probably misaligned which is usually the problem.

Mar 01, 2015 | Craftsman 1/2 HP CHain Drive Garage Door...

1 Answer

Liftmaster GDO goes up 1/2 way and stops,springs are fine.


The Liftmaster openers have 4 movement switches, a )opening and b) closing limit and c) opening and d) closing force. First check the door for smooth operation by opening the door by hand (disconnect from the opener with the release cord). Any binding should be felt this way. It is possible for a binding hinge, roller or torsion springs to add too much drag and cause the force switch to shut off the motor. Hinges, roller shafts and torsion springs should be lubricated at least annually with a non oily spray (silicone or teflon spray). Not WD-40 or 3-in-1! A light band of lube should be applied to the torsion spring coils. If the door can be operated smoothly by hand, then adjust the closing force switch 1/4 turn at a time. This is a safety device do not use it to overcome another problem!

Aug 15, 2014 | liftmaster Garage Door 1/2 Hp

1 Answer

I have an access master door opener..it goes up about 6 inches and stops, hit switch again, goes down, hit switch again goes up about two feet, hit switch again goes down, third time switch nothing until...


Door sensors have nothing to do with door opening. Only closing. It sounds like you have a bad gear in the motor unit. Remove the cover and it will be obvious if the gear is bad.

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

1 Answer

Needs proper adjusment procedures


Check if your garage door is properly balanced. Pull the red handle to release the door and manually open it. It should stay up when opened all the way. Next, pull the door down to waist level. It should stay there. If not, the lift springs need adjustment, and that may be why the opener keeps reversing.

May 06, 2009 | Office Equipment & Supplies

1 Answer

CRAFTSMAN 1/2 HP OPENER


Ok well the best advise I can give you is to open up your opener case should be a 1/4 nut driver or a Philips head screw driver. Make sure to unplug it first. Once the case is off, find a reqtangle black box with three white plastic screws they are what controls the limits. Chances are they got knocked off wheny ou were putting in the gear. check to make sure the wires are hooked up and find the placement of the limits make sure they can touch each other. Little tip I do for my customs is get a piece of sand paper and rub it agaist the metal contacts for the limits only. (after time lift master openers bind up a film and dont stop where they supposed to.) If your still not sure how the limits work plus in the opener and run it make sure not to put your hands inside the opener and nothing esle is in the way. Then adjest the limits as needed. That should take care of you if not go ahead and make another post ill check back with you.

Feb 09, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

CRAFTMAN 1/2 HP OPENER


You say it only opens two feet?? Then closes?? If I may if you a little bit more costly option. Dont replace the gears. They used to be really good 8 years ago but the way they make the gears now there too soft and often strip out much faster. I would suggest that you do what we call a motor head change out. Take off your old chain drive motor head and buy a new one. Pretty simple. Two things though one always make sure you put the new one in with the door down. And the traveler in the down position ( The traveler is the metal thing hooked up to the chain) but far and your gear that you have it sounds to me that you dont have the gears close enough.. but 100 percent on that but a door should never close on it own. It's not safe.

Feb 09, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Craftsman GDO, Model 139.53600. moves 4inches up/ down


Find the increase travel adjustment screw and turn it clockwise 1/4 to 1/2 turn.

Jan 14, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Lift master 1265lm 1993


check and see if a spring is broke on either side above the door in the middle. (big springs) that's my problem.

Aug 30, 2008 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Craftsman GDO Will not close


readjust the sensor controls on the side of the unit

Dec 28, 2007 | Sears Craftsman LiftMaster Chamberlain...

Not finding what you are looking for?
liftmaster Chamberlain Garage Door Opener Transmitter 300MC Logo

442 people viewed this question

Ask a Question

Usually answered in minutes!

Top liftmaster Electrical Supplies Experts

Mike

Level 3 Expert

4334 Answers

Gil Shultz

Level 3 Expert

3368 Answers

ray gallant

Level 3 Expert

40945 Answers

Are you a liftmaster Electrical Supply Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...