The adsorption of Ar on planar structureless substrates of alkali metals, alkaline-earth metal Mg, CO₂, and Au was analyzed by applying a density functional formalism which includes a recently proposed effective attractive pair potential conditioned to Ar. It is shown that this approach reproduces the experimental surface tension of the liquid-vapor interface over the entire bulk coexistence curve for temperatures T spanning from the triple point T_t up to the critical point T_c. The wetting properties were studied over the entire range temperatures T_t-T_c. It was found that Ar wets all the investigated surfaces. The adsorption isotherms for alkali metals exhibit first-order phase transitions. Prewetting lines were resolved even for the less attractive surfaces. In the cases of Mg, CO₂, and Au a continuous growth for T ≥ T_t was obtained. A comparison with experimental data and other microscopic calculations is reported.