The dependence of the two-body and three-body interactions in the ArnCO2 cluster upon the intramolecular asymmetric stretching coordinate of CO2 is studied by the ab initio method. In the T-shaped binary complex Ar-CO2, the influence of the components of the interaction energy on the shift of the asymmetric stretching frequency of CO2 (nu(3)) is estimated within a one-dimensional vibrational model and compared with the experimental data of Sperhac, Weida, and Nesbitt [J. Chem. Phys. 101, 2202 (1996)]. The interaction energy is dissected into Heitler-London, induction, and dispersion energies and their respective intrasystem correlation corrections. The redshift represents a delicate balance of these effects on the upsilon=0 and upsilon=1 levels. The highly correlated treatment is required to describe the dependence of two-body potential upon the stretching coordinate. The supermolecular coupled cluster calculations with the single, double, and noniterative triple excitations reproduce the shift observed by Sperhac et al. with excellent accuracy. In the Ar2CO2 trimer with the two Ar atoms in equatorial positions, the influence of the three-body interaction components on the upsilon=0 and upsilon=1 levels is analyzed. A model of the three-body potential, including three nonadditive components, exchange, induction, and dispersion is applied. It describes the departure from additivity of the two-body shifts observed by Sperhac et al. with excellent accuracy. The analytical models of the energy components are also discussed.