liftmaster Recent Questions, Troubleshooting Help & Support

Check the light bulbs in the opener. Newer fluorescent or LED bulbs can generate enough radio frequency interference that the normal signal levels from the remote will be inadequate. Of course, make sure the remote batteries are fresh.

check the liftmaster web-site. also any garage door sites may have parts offerings. google the part number as well.

good photo, you can tr to replace the starter solenoid, check all wiring and connections, safeteys etc.

pop the cover off the code box, instructions are printed on the back of the cover

Well, I don't think that disconnecting the garage door from the garage door opener would affect function.

The lightning strike could have destroyed the circuitry inside the garage door opener, seeing that it won't operate with the wall switch or remotes.

It's likely that a board was fried by the lightning which would render the garage door inoperable.

colder weather solidifies the grease to add extra friction on the moving door in the track. Increase the downward close pressure. Its a screw on the motor box. There are 2 sets of screws one for open and close pressure the other set for close and open distance

Manuel the Mexican or manual the book?

If the track is a screw thread, then just latch the door anywhere along the track, and it will realign itself. If the track is a chain-drive... then push door up until it clicks into latch. Gene If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Verify you have power at the opener. If the lights flash upon close - you are good. Next, make sure the photoeyes are aligned properly. the master photoeye will always have power. The second will light up when it sees the master unit. If they are aligned, replace them (they do fail). You can also temproarily jumper the wires at the opener to see if the door operates. This will confirm a bad sensor.

Hi Richard...call LiftMaster Technical Support.... 800-528-5880 Regards, Dennis

Under the battery compartment, there should be a set of small switches, with a number "1" and "2" on either side. Move the switches to match the same position(s) as the ones on the door opener (or receiving unit.)

here is a YouTube video on battery replacement. http://www.youtube.com/watch?v=9GYqN5_DRHY

The question is confusing. What did you replace the battery in, the battery back up power supply or the transmitter? The 300MC is just the transmitter and changing that battery has nothing to do with whether the main power unit will function if you unplug it. Now, if you replaced the large battery in the opener itself, it needs to fully charge before it will function properly so give it about 24 hours to charge with the power cord plugged in and then try again. It should work IF you attached the wires to the CORRECT terminals on the battery, positive to positive and negative to negative. If you did not, reverse them, allow the battery to charge 24 hours plugged in and try again. If you installed it in reverse there is a chance you fried the circuit board and that means you will not be able to use the backup feature although the opener may function normally without it.

The limit switch is bad on the track If you need further help, reach me via phone at https://www.6ya.com/expert/scott_87482045335a4757

It's sometimes easier and cheaper to replace at that point if the gear is bad chances are ther is more bad If you need further help, reach me via phone at https://www.6ya.com/expert/scott_87482045335a4757

Take the back cover off the code is numbered pins so you can set it If you need further help, reach me via phone at https://www.6ya.com/expert/scott_87482045335a4757

Click the learn button on the receiver followed by the remote. See e.g. http://www.liftmaster.com/CatalogResourcesV3/en-us/shared/files/tucmanuals/114A4109.pdf