LiftMaster 41A5640 Limit Switch Assembly

The LiftMaster 41A5640 Limit Switch Assembly is a replacement part for select LiftMaster garage door openers that use a mechanical travel limit system. This assembly contains the paired limit switches and wire harness that signal the opener to stop at the programmed open and close positions. It works in tandem with the opener’s threaded shaft and limit adjustment nuts, restoring consistent travel control when doors overrun, stop short, or fail to reach the correct stop points. Commonly found in many AC chain- and belt-drive units from LiftMaster and compatible Chamberlain/Craftsman models from the Chamberlain Group family, this part maintains reliable door positioning in residential garage door opener applications.

Installation typically involves disconnecting power, removing the opener’s light lens/cover, replacing the internal switch bracket and harness, and then readjusting travel using the open/close limit nuts per the owner’s manual. After installation, verify safe operation and test door balance, photo-eye alignment, and safety reversal. This 41A5640 limit switch assembly is intended only for models designed for a two-switch mechanical limit system; it is not interchangeable with electronic travel modules or RPM sensor assemblies used on other opener types. Always confirm compatibility by matching 41A5640 to the part number in your opener’s manual or the label on the existing component.