Question about Sears Craftsman LiftMaster Chamberlain Garage Door Opener Wireless Keypad Model 976LM Security+

2 Answers

My garage door only opens then 1ft then returns 1fts

Today I replaced my Drive gear for my 1/2hp Craftsman garage door opener(model #139.18856) and now my door will only open 1ft then closes 1ft with the push of the button once. I have adjusted the Force up and down and it does make a difference. Both my senors are fine and aligned. I have also play around with the adjust limits and the it makes no difference. I have lucicated the the rollers, chain and the gears. I have reset the chain several times and nothing changes. All the gears are aligned and seem to be running smoothly.
I don't have manual and the unit is 10 years.

What do I do?

Posted by on

  • jasonestick3 Jan 08, 2009

    The door runs smoothly when it is dis-engaged. I have cleaned the the senors. What is the serrated cap? how would I go about making sure the limit assy is connected to the photo interupter board?

    Thanks
    Jason


  • jasonestick3 Jan 08, 2009

    Also the green light on the back of the unit is flashing?

×

2 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

  • Master
  • 15,935 Answers

Does it move smoothly when you use the manual release?
If your motion sensors check good and door operates ok manually try turning down force dial clockwise, It is typically at 1 for a single width door or 3 for a double. Increase to 5 or 7 for test purpose. As doors get older their springs weaken. If you have increased down force threshold and the door continues to reverse, the RPM sensor is the culprit. There is no way to override or test this sensor by using the hand unit or the wall control. When this sensor goes bad the door will start down and the logic board will not receive the electronic pulses and it will reverse. It is this sensor that causes the door to reverse when it runs into something. The motor stalls, the logic board doesn't receive these pulses and it reverses. This little circuit board is located at the door end of the motor shaft and every door company has them in stock. Take the cover off the unit and you will see a black cap on the end of the shaft that rotates between infrared sensors. That small circuit board is the culprit. Make sure you reinstall serrated cap so that as it turns it breaks sender receiver path on new board.
There are also adjustments on the "effort" your garage door uses. When installed they are set at the lowest effort that will work. Over time the door may get harder to move (less lubrication, dirt, rust). There should be a knob on your opener that adjusts the effort. I'd try to turn that slightly and see if it solves your problem. Keep adjusting slightly until the door works properly.

If that does not do it you might have a problem with the "eyes" that prevent the door from closing when someone is under the door (installed near the floor on either side of the garage door). I've had leaves interfere with my opener - so make sure the eyes are clear with no cobwebs and check to see if the wires from the eyes are connected - I've had mine corrode and cause problems

Posted on Jan 08, 2009

  • blueextc3221
    blueextc3221 Jan 08, 2009

    Please adjust the FORCE knob, and see if the door operates properly.

×

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

    Sniper:

    An expert who has posted more than 50 answers, of which 90% or more were rated as helpful.

  • Expert
  • 98 Answers

The wire harness (4 wire) from the limit assy is not connected to the photo interupter board.

Posted on Jan 08, 2009

  • Joseph Chapman
    Joseph Chapman Jan 08, 2009

    How many times does it flash? 


×

Add Your Answer

Uploading: 0%

my-video-file.mp4

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

×

Loading...
Loading...

Related Questions:

1 Answer

Don't know Mod. No. lost installation manual, approx. 5 yrs. old Need installation manual.


About 496,000 results (0.43 seconds) Search Results

    [PDF]GARAGE DOOR OPENER Model 3265 1/2 HP ... - LiftMaster

    www.liftmaster.com/.../en.../tucmanuals/114a3044.pdf Chamberlain GroupFasten the manual near the garage door after installation. .... This garage door openerhas been designed and tested to offer safe service provided it is installed, ...

    Manuals Download Craftsman Garage Door Opener Model ...

    www.craftsman.com/search=manuals%20download%20crafts...

    CraftsmanCraftsman has the best selection of Garage Door Openers in stock. Get the Garage Door Openers you want from the brands you love today at Craftsman.

    Craftsman 1/2 HP Chain Drive Garage Door Opener - Sears

    www.craftsman.com > ... > Garage Door Openers

    Craftsman1/2 hp Chain Drive Garage Door Opener Opens by Remote, Inside and from Car Enjoy a great end to every day by ... Owners manual - English (Warranty).

    Free Craftsman Garage Door Opener User Manuals ...

Feb 03, 2016 | Garage Doors

1 Answer

Craftsman garagedor opener


Remove the cover from the motor housing and check the drive gear. It is a white nylon gear and will be obvious if it is bad.

Jul 13, 2012 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Loud, grinding noise from garage door opener


Remove the cover from the motor housing and check the drive gear.

Jul 09, 2012 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Motor runs but door does not open on my craftsman 1/2 h.p. Garage door opener


Remove the cover from the motor unit and check the drive gear. It is a white nylon gear just in front of the motor and is most likely stripped.

May 14, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

The craftsman garage door opener only opens door 6 inches to about 30 inches and won't go any higher model 139 .53930D


Check your door springs. One may be broken. Also check the drive gear. It is a white nylon gear just in front of the motor.

Mar 11, 2010 | Sears Craftsman LiftMaster Chamberlain...

3 Answers

Motor hums but door doesn't move. If I disconnect door and give chain a horizontal poke, it will move. When I reconnect door it returns to humming, without movement.


Remove the cover from the motor unit and you will find the drive gear has stripped. White sawdust all over. The part number for the gear kit is 41A2817 and it comes with instructions. It is available at any good door opener service company.

Feb 04, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

The nylon drive gear on Craftsman Garage Door keep stripping


The most common reason for this is a door that is too heavy. Release the door from the opener and lift it by hand. If it is heavy to you it is heavy for the opener. Be sure after replacing the gear to lubricate it heavily with the lubricant supplied with the gear. You can't apply too much.

Jul 05, 2009 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Craftsman Garage Door Opener - Gears need to be fixed


Unplug the unit and remove the cover, usually eight screws, if you see a lot of white dust in the cover check the nylon drive/worm gear, they will need to be replaced.

Apr 10, 2009 | Sears Craftsman LiftMaster Chamberlain...

2 Answers

Craftsman Garage Door Opener Won't Open


When mine did this, it was because the nylon gears that drive the chain had stripped. My wife had to live without the opener for a week or more, but I was able to find a new gear kit online and replace the damaged gears. It wasn't difficult.
The other option is to buy a new opener.

Dec 03, 2008 | Sears Craftsman LiftMaster Chamberlain...

Not finding what you are looking for?
Sears Craftsman LiftMaster Chamberlain Garage Door Opener Wireless Keypad Model 976LM Security+ Logo

364 people viewed this question

Ask a Question

Usually answered in minutes!

Top Sears Garage Doors Experts

Al Clark

Level 2 Expert

290 Answers

Cindy Wells

Level 3 Expert

4756 Answers

Pieter Vleeshouwers

Level 3 Expert

1410 Answers

Are you a Sears Garage Door Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...