Chamberlain 3500 - 1/2HP Series Owner's Manual page 35

Situation
The door opens but
won't close:
The door reverses for
no apparent reason
and opener lights
don't blink:
The door reverses for
no apparent reason
and opener lights
blink for 5 seconds
after reversing:
The opener lights:
The opener strains or
maximum force is
needed to operate
door:
The opener motor
hums briefly, then
won't work:
The opener won't
operate due to
power failure:
The chain droops
or sags:
Having a Problem?
Probable Cause & Solution
1. If the opener lights blink, check the safety reversing sensor. See page 23.
2. If the opener lights do not blink and it is a new installation, check the down force.
See Adjustment Step 2, page 29. For an existing installation, see below.
Repeat the safety reverse test after the adjustment is complete.
1. Is something obstructing the door? Pull the manual release handle. Operate the door
manually. If it is unbalanced or binding, call for professional garage door service.
2. Clear any ice or snow from the garage floor area where the door closes.
3. Review the force adjustment procedures on page 29.
4. If door reverses in the fully closed position, decrease the travel limits (page 28).
Repeat safety reverse test after adjustments to force or travel limits. The need
for occasional adjustment of the force and limit settings is normal. Weather
conditions in particular can affect door travel.
Check the safety reversing sensor. Remove any obstruction or align the receiving eye.
See page 23.
. . . don't turn on:
Replace the light bulbs (75 watts maximum). Use a standard neck garage door opener
bulb if regular bulb burns out.
. . . don't turn off:
Is the Light feature on ? Turn it off.
The door may be out of balance or the springs are broken. Close the door and use the
manual release 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 professional garage door serviceman. Do not
increase the force to operate the opener.
1. The garage door springs are broken. See above.
2. If the problem occurs on the first operation of the opener, door may be locked. Disable
the door lock . If the chain was removed and reinstalled, the motor may be out of phase.
Remove the chain; cycle the motor to the down position. Observe the drive sprocket.
When it turns in a clockwise direction and stops in the down position, reinstall the chain.
Repeat the safety reverse test after the adjustment is complete.
1. Use the manual release to disconnect the trolley. The door can be opened and closed
manually. When the power is restored, press the Door Control push bar and trolley will
automatically reconnect (unless trolley is in lockout position.) See page 32.
2. 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.
It is normal for the chain to droop slightly in the closed door position. Use the manual
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 2x4 laid flat, no
adjustments are needed. (See page 11.)
(continued)
35