Chamberlain 3800C Owner's Manual page 24

Having a Problem? (Continued)
5. 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
control console and the motor unit.
• Clear memory and re-program all remote controls.
6. The door doesn't open completely:
• Check power door lock.
• Is something obstructing the door? Is it out of
balance, or are the springs broken? Remove the
obstruction or repair the door.
7. The door opens but won't close:
• Check cable tension monitor.
• If the opener lights blink, check the safety reversing
sensor. See Installation Step 9.
• 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.
8. The door reverses for no apparent reason and
opener lights don't blink:
• Check cable tension monitor.
• 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.
9. 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 9.
10. 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 door. 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.
11. 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 power
door lock.
12. The opener won't operate due to power failure:
• Manually open the power door lock.
• Use the emergency release handle to disconnect the
door. The door can be opened and closed manually.
When power is restored, pull manual release a
second time.
• If a Battery Backup Unit is connected, the opener
should be able to operate up to 20 times
without power.
13. Door loses limits.
• Collar not tightened securely. Tighten collar
(see Assembly Steps 1 and 2) and reprogram limits
(see Adjustment Step 1).
14. The operator moves when the door is in
operation:
• Some minor movement is normal for this product. If it
is excessive the collar will wear prematurely.
• Check to make sure the torsion bar is not moving
left/right excessively.
• Check to make sure the torsion bar is not visibly
moving up and down as it rotates.
• Check that the operator is mounted at a right angle to
the jackshaft. If not, move the position of the
mounting bracket.
15. Power lock makes noise when operating.
• Call Liftmaster ®
24
dealer for replacement power lock.