Chamberlain LiftMaster PROFESSIONAL SECURITY+ 2500DC Manuel D'instructions page 30

Having a Problem? (Continued)
6. The garage door opens and closes by itself:
• Be sure that all remote control push buttons are
off.
• Remove the bell wire from the door control
terminals and operate from the remote only. If this
solves the problem, the door control is faulty
(replace), or there is an intermittent short on the
wire between the door control and the motor unit.
• Clear memory and re-program all remote controls.
7. The door doesn't open completely:
• Is something obstructing the door? Is it out of
balance, or are the springs broken? Remove the
obstruction or repair the door.
8. The door opens but won't close:
• If the opener lights blink, check the safety
reversing sensor. See Installation Step 10.
• If the opener lights don't blink and it is a new
installation. See Adjustment Step 2. For an
existing installation, see below.
Repeat the safety reverse test after the adjustment
is complete.
9. The door reverses for no apparent reason and
opener lights don't blink:
• Is something obstructing the door? Pull the
emergency release handle. Operate the door
manually. If it is unbalanced or binding, call a
trained door systems technician.
• Clear any ice or snow from the garage floor area
where the door closes.
• Review Adjustment Step 2.
Repeat safety reverse test after adjustments.
10. The door reverses for no apparent reason and
opener lights blink for 5 seconds after
reversing:
• Check the safety reversing sensor. Remove any
obstruction or align the receiving eye. See
Installation Step 10.
11. The opener lights don't turn on:
• Replace the light bulbs (100 watts maximum). Use
a standard neck garage door opener bulb if regular
bulb burns out.
12. The opener lights don't turn off:
• Is the Light feature on? Turn it off.
13. The opener strains to operate door:
• The door may be out of balance or the springs
may be broken. Close the door and use the
emergency release handle to disconnect the
trolley. Open and close the door manually. A
properly balanced door will stay in any point of
travel while being supported entirely by its springs.
If it does not, disconnect the opener and call a
trained door systems technician.
14. The opener motor hums briefly, then won't
work:
• The garage door springs may be broken. See
above.
• If the problem occurs on the first operation of the
opener, door may be locked. Disable the door lock.
15. The opener won't operate due to power
failure:
• Use the emergency release handle to disconnect
the trolley. The door can be opened and closed
manually. When power is restored, press the Door
Control push bar and trolley will automatically
reconnect (unless trolley is in lockout position.)
See page 28.
• The Outside Quick Release accessory (for use on
garages with no service door) disconnects the
trolley from outside the garage in case of power
failure.
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