New multireference, configuration-interaction potential energy surfaces are reported for the interaction of Ar with the CH radical in its ground (X (2) Pi) and second excited (B (2) Sigma(-)) electronic states. These potential energy surfaces are then used in an adiabatic analysis of the rovibronic levels of the ArCH(X) and ArCH(B) van der Waals complexes. A qualitative discussion of the expected features in the B <-- X electronic spectrum of ArCH is presented, and these are compared with the experimental spectrum reported earlier by Lemire et al. [J. Chem. Phys. 99, 91 (1993)].