A self-adjusting balance valve controller controls water flow through a hydronic emitter in a heating and/or cooling temperature control system. The valve controller obtains a measured temperature differential between an inlet and an outlet of the hydronic emitter and determines a displacement of a coupling pin from the measured temperature differential. The valve controller then instructs a driving mechanism to move, through a coupling mechanism, the coupling pin to adjust a valve that results in a desired water flow through the hydronic emitter. The valve controller may maintain a stable temperature differential at a desired differential value, which may be obtained through a user interface or from a memory device. Moreover, the desired differential value may vary with different times of operation or temperature control situations.