Question about liftmaster Chamberlain Garage Door Opener Transmitter 300MC

1 Answer

I have a Automatic Doorman Model 455, problem is door goes down with no trouble, but lifting it goes about 10" and stops. I have changed the "V" belt, the problem still exists. I did an ampere draw test, amp draw should be around 4.5amps, when going down amp draw is 2.3 amps, when lifting the draw is 6.9 amps which is way too much. I think the problem after 22 years of no problem usage, the motor is weakening. What is diagnosis? Email- oilman1055@aol.com Thanks

Posted by on

1 Answer

  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer

You are probably right about the motor going.Does it get to a point where the door stops and the motor is making a humming sound? If so the motor is going for sure...In the mean time to get you by,try putting more tension on the spring of your door to give the electric door opener a little extra help as its opening.

Posted on Jan 03, 2011

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

Where does the wires hook from motor to where? Automatic Doorman 455


Is the door opener motor bad? You say, "the wires"--is there a plug on the end of the wires that can be plugged into an outlet? If so, thy plugging it into an extension cord instead of the outlet in the garage ceiling and see if you still trip a breaker. If you do, it's a problem in the opener. There are things to do to locate the source of the problem. It the breaker trips instantly when you press the button then there's a dead short somewhere. Does the motor get warm or hum before the breaker trips? If so, then maybe the door mechanism is locked up and the motor cant turn. Did you check to see if your garage door is locked?

Nov 26, 2014 | Building Materials

1 Answer

Installed two new springs on automatic doorman model 455 and it won't close or open. chain will not move door where are adjustment screws? I think that may be the problem


Does it make a noise? Did it run before you changed the springs? Did you replace springs on opener or on the door? What adjustment screws are you looking for? Do you think they went out of adjustment when you changed the springs?

Sep 04, 2011 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

Does anyone know where I can get the 9 tooth chain sprocket (not the one on the unit) for a Doorman 455?


If you are looking for the sprocket that goes on the door end of the T-rail you can call any Chamberlain or Liftmaster dealer in the yellow pages. They might even sell you a used one off an old opener they have changed out.

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

1 Answer

Automatic Doorman model 455 learn button location?


The button should be on the back of the motor unit. You may have to remove a light lens to find it.

Aug 01, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

I have an Automatice Doorman model 455 garage door opener. I recently changed the battery for its remote control. How do I reprogram the remote control?


Your opener is very old and not only are there no parts available but it is not a programmable system. Your best bet is to buy something more up to date which will be much safer to operate.

Jul 29, 2010 | Sears Craftsman LiftMaster Chamberlain...

1 Answer

I have an Automatic Doorman 455 garage door opener. The door while going down hit the top of a garbage can and instead of going back up, was stuck with motor running for 2-3 mins. before I pulled the plug...


I am assuming that the motor runs but the belt slips (until you give it an assist).
The belt got glazed when it sat there stuck with the motor running, and now it is too slippery.
Take the belt off. If the pulleys have a blackened coating (melted rubber) in the v, you should clean them up. Steel wool works well for that.
You might be able to salvage the belt by roughing up the friction surface with sandpaper (about 100 grit). If the belt is old and has cracks, just buy a new belt.

Mar 30, 2010 | liftmaster Chamberlain Garage Door Opener...

2 Answers

Chamberlain Liftmaster Professional 1/2 HP


Okay...upon further inspection, my left spring has broken in two. Going to call around for some quotes to replace the spring. Thanks for the suggestions.

Jul 21, 2008 | Sears Craftsman LiftMaster Chamberlain...

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

673 people viewed this question

Ask a Question

Usually answered in minutes!

Top liftmaster Electrical Supplies Experts

Vince Heuser

Level 2 Expert

118 Answers

tamska1102

Level 1 Expert

28 Answers

ray gallant

Level 3 Expert

42828 Answers

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

Answer questions

Manuals & User Guides

Loading...