Abstract : We investigate the norm identity $\|uC_\varphi + T\| = \|u\|_\infty + \|T\|$ for classes of operators on $C(S)$, where $S$ is a compact Hausdorff space without isolated point, and characterize those weighted composition operators which satisfy this equation for every weakly compact operator $T : C(S)\rightarrow C(S)$. We also give a characterization of such weighted composition operator acting on the disk algebra $A(D).$
