Craftsman 1/2 HP GARAGE DOOR OPENER 139.53978SRT - Manual (Page 28)

Adjustment Section: Pages 28 - 30
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.
If anything interferes with the door’s upward travel, it
will stop. If anything interferes with the door’s
downward travel (including binding or unbalanced
doors), it will reverse.
To operate the opener, press the Door Control push
bar or 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 30).
Adjustment procedures are outlined below.
Read the procedures carefully before
proceeding to Adjustment Step 2. Use a
screwdriver to make limit adjustments. Run the
opener through a complete travel cycle after
each adjustment.
NOTE: Repeated operation of the opener during
adjustm ent procedures m ay cause the m otor to
overheat and shut off. Sim ply wait 15 m inutes and
try again.
Improper adjustment of the travel limits will
interfere with the proper operation of the safety
reverse system.
The door might not reverse
properly when required and could seriously
injure or km someone under It. Test the safety
reverse system following all adjustments to the
travel limits. See page 30.
Limit
Adjustment
Bolt
Adjustment Label
How and When to Adjust the Limits
• If the door does not open completely, but
opens at least i\ye feet:
Increase i//? travel. Turn the UP limit adjustment
screw clockwise. One turn equals 2" of travel.
NOTE: To prevent the trolley from hitting the cover
protection bolt, keep a m inim um distance of 2-4"
between the trolley and the bolt
• 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 dose completely:
Increase ctotw? travel. Turn the DOWN limit
adjustment screw counterclockwise. One turn
equals 2“ of travel.
If the door still won't close completely and the trolley
bumps into the trolley stop bolt (see page 4 or 5), try
lengthening the door arm (see page 26) and
decreasing the down limit.
• If the opener reverses in fully closed position:
Decrease itowr? travel. Turn the DOWN limit
adjustment screw clockwise. One turn equals 2" of
travel.
• If the door /eve/seswhen closing and
there is no visible interference to travel cycle:
If the opener lights are flashing, the Safety
Reversing Sensors are either not installed,
misaligned, or obstructed. See Troubleshooting,
page 23.
Test the door for binding: Pull the emergency
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.
28