Liftmaster makes a number of opening devices but may be best known for its residential garage door openers. These units come with some self-diagnostic tools which can assist you in determining the problem if your machine ceases to work properly. Attempt to troubleshoot the issues on your own before calling customer service or paying a technician to fix the problem for you.
Door Won't Close; Lights Blinking
If your Liftmaster Professional garage door will not close, and the light bulbs on the motor unit are blinking, check to make sure the safety sensor at the bottom of the door is properly installed and aligned and is free of any interference. If it is not connected properly, the garage door cannot move in the down direction.
Blinking lights could indicate other problems as well: Refer to the Diagnostic Chart in your owner's manual.
Remote Controls Fail
If your remotes will not cause your door to open or close, and the door control is blinking, it may be in "Lock Mode." You will have to deactivate it; refer to the instructions in the "Using the Wall Mounted Door Control" section of the manual. If the codes on your remotes have been accidentally erased, you must reprogram them.
If your door still does not respond, check the LED flashes on the motor unit and refer to the Diagnostic Chart in the manual.
Door Opens On Its Own
If the door begins to reverse on its own after fully closing, the problem may be with the force and limit settings. Cold weather may be a reason for this. Once you make adjustments, complete the "Safety Reverse Test," which can be found in the owner's manual. Manually check the door for balance problems, or for binding--when the garage door will not move easily because the tracks are not properly aligned to guide the rollers. Your owner's manual will have instructions in the "Adjustment Step 2, Adjust the Force" section.