Adjustment Section: Pages; Travel Limit Adjustments; Adjust Up/Down Limits - Chamberlain 1255GM Owner's Manual

Adjustment Step 1
Adjust the UP and DOWN Limits
Do not make any limit adjustments until the
Safety Reversing Sensors are completely
installed.
Limit adjustment settings regulate the points at
which the door will stop when moving up or down.
The door will stop in the up direction if anything
interferes with door travel. The door will reverse in
the down direction if anything interferes with the
door travel (including binding or unbalanced doors).
To operate the opener, press the Door Control
button. Run the opener through a complete travel
cycle.
• Does the door open and close completely?
• Does the door stay closed and not reverse
unintentionally when fully closed?
If your door passes both of these tests, no limit
adjustments are necessary unless the reversing test
fails (see page 26).
Adjustment procedures are outlined below. Run
the opener through a complete travel cycle after
each adjustment.
Repeated operation of the opener during
adjustment procedures may cause the motor to
overheat and shut off. Simply wait 15 minutes
and try again.
Read the procedures carefully before continuing on
to Adjustment Step 2. Use a screwdriver to make
limit adjustments.
If the door does not open completely
but opens at least five feet
Increase up travel. Turn the UP limit adjustment
screw clockwise. One turn equals 2" of travel.
If door does not open at least 5 feet:
Adjust the UP (open) force as explained in
Adjustment Step 2.
If the door does not close completely
Increase down travel. Turn the DOWN limit
adjustment screw counterclockwise. One turn
equals 2" of travel.
If door still won't close completely, try lengthening
the door arm. (See page 22.)
If you have adjusted the door arm to the maximum
length and the door still will not close completely,
lower the header bracket. See Installation Step 1,
pages 8 and 9.
Adjustment Section: Pages 24 – 26
How and When to Adjust the Limits
Improper adjustment of the travel limits will
interfere with the proper operation of the
safety reverse system. The door might not
reverse when required and could seriously
injure or kill someone under it. Test the safety
reverse system following all adjustments to
the travel limits. See page 26.
If the opener reverses in fully closed position
Decrease down travel. Turn the DOWN limit
adjustment screw clockwise. One turn equals 2" of
travel.
If the door reverses when closing and
there is no visible interference to travel cycle
If the opener lights are flashing, the Safety Reversing
Sensor is obstructed. Remove the obstruction.
Test the door for binding: Pull the manual release
handle. Manually open and close the door. If the door
is binding, call for garage door service. If the door is
not binding or unbalanced, adjust the DOWN (close)
force. See Adjustment Step 2.
24
WARNING
INCREASE TRAVEL
DOWN
UP
Left Side
Panel
INCREASE TRAVEL
DOWN
UP
Adjustment Label
Limit
Adjustment
Screws