Chamberlain 4620, 4620-2 Adjust the UP and DOWN Limits, reverses, How and When to Adjust the Limits, If door does not open at least 5 feet:, If the door does not close completely:

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.

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 push 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. 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 proceeding to Adjustment Step 2. Use a screwdriver to make limit adjustments.

WARNING

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 kill someone under it. Test the safety reverse system monthly, and following all adjustments to the travel limits. See page 30.

				+
1	2			3
	8	1	8	1
	7	3	7	3
	5			5
				+

	Travel Limit
	Adjustment
Right Side Panel	Screws

LIMIT ADJUSTMENT		+	Adjust UP Travel
LABEL
	+		Adjust DOWN Travel

How and When to Adjust the Limits

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. (Page 26.)

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 12 and 13.

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 Sensors are either not installed, misaligned, or obstructed. See Troubleshooting, page 22.

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.

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