After an assessment of the equil. properties of Ar2 (De~75 cm-1, Re~7.32 Bohr) as detd. in supermol. coupled-pair functional calcns. in the limit of high angular momentum basis functions, the potential energy surface for interaction of an Ar atom with the CO mol. is presented. The calcd. potential energy surface has its abs. min. of De = 71 cm-1 at a T-shaped geometry. The barriers for rotation around the oxygen and carbon end of the complex have been found to be 13 and 21 cm-1, resp. The performance of averaged coupled-pair functional and averaged quadratic coupled-cluster techniques for calcn. of interaction energies of Ar2 and Ar-CO and for detn. of electrostatic moments and polarizabilities of the CO mol. is briefly discussed as well.