LiftMaster MERIK SECURITY+ 790LMK Manual Del Propietário página 35

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 fl oor 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 briefl y, then won't work:
• The garage door springs may be broken. See above.
• If the problem occurs on the fi rst 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 33.
• 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.
16. The chain droops or sags:
• It is normal for the chain to droop slightly in the closed
door position. Use the emergency release rope and handle
to disconnect the trolley. If the chain returns to the normal
height when the trolley is disengaged, and the door reverses
on a 38 mm obstruction, no adjustments are needed. See
page 15.
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