The LiftMaster 50-104-1 Interior Air Switch SPDT Assembly is a pneumatic, air‑actuated control designed for interior mounting on LiftMaster commercial door systems. Activated by air pressure through connected tubing rather than a direct electrical push button in the wet zone, it’s commonly used for car wash doors and other wash bay or damp environments where an electrical switch cannot be exposed. The air pulse triggers an internal single‑pole, double‑throw (SPDT) switch, allowing a technician to wire the contact as normally open or normally closed to suit the operator’s control logic for open, close, or momentary functions. This replacement part helps maintain reliable, isolated control of sectional or rolling steel doors in demanding commercial applications.
As an SPDT assembly, it provides a dry-contact interface that works with many LiftMaster commercial door operators that accept external control inputs. The “Interior” designation indicates it is intended to be mounted in a protected indoor location while the air line runs to a remote actuator in the splash area, helping reduce corrosion and electrical exposure. Installation should be performed by a qualified technician following the operator’s manual and applicable safety standards (such as UL 325), ensuring correct wiring to the control terminal strip and secure air tubing connections. This LiftMaster OEM replacement supports service and upgrade needs where a pneumatic control is preferred, offering compatibility for residential/commercial facilities that require reliable door activation in wet or washdown conditions.