#1 - Vacation Switch/Lock-out Button. Press the button on the wall and see if the door will close. If it does close then the problem is most likely the "Lock Out Switch" or "Vacation Switch". Just about every opener manufacturer puts these on their wall control stations (not sure why - no one ever uses them & they're a pain - that's another rant for another day). Most wall control stations will have a "Light" button (turns light on/off), "Vacation"/"Lock Out" button (locks out the remotes) and "Open/Close" button. Try disengaging the "Vacation" switch and trying your remote. If it now works you can jump back into your car & off to your appointment. If the remote still doesn't work then keep reading.
#2 - Check the Photo-eyes. The photo-eyes (or sensors) are mounted on either side of the door near the floor. There's a Emitter sensor and a Receiver sensor. These sensors have to "look" at each other so if they are knocked out alignment (kids, lawn mowers, hoses, garbage cans bumping into them can knock them out of alignment) they can't "see" each other and the opener will refuse to close door. (Side note: if you want to override the unit you can hold the close button on the wall station until the door completely closes.)
- Check & make sure sensors are aligned
- Make sure nothing is blocking sensors (garbage bag, broom, etc. - it happens more than you would think)
- Clean the lens on each sensor - sometimes dirt or grass clippings can interfere
- Check wires to the sensors & the one's going to the power head - make sure they didn't come loose
- Check & see if sun is shining on sensors. Sometimes the sun can "blind" the sensors and cause them to think an object is blocking the opening. If this is the case the sensors may need moved further into the garage.
#3 - Check Door Close Sensitivity. If you're not comfortable with making adjustments to the opener settings (if not done correctly you could make the problem worse) then you should call a garage door professional to check the operator. If you are mechanically minded then you should get the opener manual and find out where the sensitivity settings are. Most openers have a sensitivity setting for opening the door and closing the door. Before you adjust the sensitivity disconnect the opener from the door by pulling the emergency release. Check to see how the door balances and moves. If the door is hard to open or close the problem may not be the opener. You may need to call a professional to adjust the garage door. If the door works well manually then reconnect the opener and adjust the close sensitivity. WARNING: DON'T INCREASE TOO MUCH - FOLLOW THE MANUFACTURERS RECOMMENDATIONS. If you put a 2x4 under the door & the opener doesn't reverse you need to increase the sensitivity or someone could get injured.
If you've checked all of the above and the opener still doesn't close the door - pull the emergency release (usually a red cord hanging from the trolley) and close the door manually. Lock the interior lock on the door (if it has one). Call your local garage door professional. There may be something else going on with the opener. The sensors or the logic board in the opener may not be functioning properly and need replaced.
If one of the above solutions worked then you just saved yourself a bill from your local garage door professional.
Remember, if you don't feel comfortable doing any of the above and get frustrated easily (some people don't like to do troubleshooting) then just call your friendly garage door service tech. They should be able to help you out in no time.