The Trane MOD00145 Economizer UEM (Unitary Economizer Module) is an HVAC control component designed to interface the unitary control processor with the economizer actuator motor. It regulates outdoor air damper operation according to system commands, supporting controlled ventilation and free cooling when outdoor conditions are suitable. This module is used in compatible Trane Voyager... https://www.partshnc.com/trane-mod00145-economizer-uem-module