A. O. Smith 731A Three-Phase Induction Electric Motor

The Century/A.O. Smith 731A is a compact 1/4 HP electric motor designed for HVAC blower duties, delivering 115/208-240V operation and 1140 RPM on a 5-5/8-inch frame with a Totally Enclosed Fan-Cooled (TEFC) enclosure. This voltage range and speed make it a versatile replacement for Century equipment and many aftermarket installations, commonly used in unit heaters, air handlers, and blower assemblies where reliable, modest-torque airflow is required. The model number 731A identifies a widely cataloged Century/A.O. Smith motor, and distributors consistently list it as 1/4 HP, 115/208-240V, 1140 RPM, with a 5-5/8" TEFC frame. TEFC construction provides protection against dust and moisture in HVAC environments, helping maintain performance in typical installation conditions. As a replacement option, it appears across multiple retailers and OEM catalogs, supporting legacy Century systems and compatible aftermarket builds.