The total fragmentation pathway of Ar-HCl upon ultraviolet photoexcitation, Ar-HCl + hv --> H + Ar + Cl, is studied using a wave packet treatment. Kinetic-energy distributions of the hydrogen fragment are calculated for different excitation energies of the cluster. The distributions display a structure of peaks that can be assigned to successive collisions of hydrogen with Ar and Cl before dissociating. Up to four peaks with decreasing intensity as the kinetic energy decreases are found in the distributions in the range of kinetic energies investigated. The two most intense peaks appearing at high kinetic energies are assigned to the first H/Ar collision, the main peak associated with weak collisions, and the other one associated with harder collisions. Two additional peaks at lower kinetic energies are assigned to subsequent hydrogen collisions, i.e., a second collision with Cl and a third one with Ar again, respectively. The structure of the H fragment kinetic-energy distributions is the signature of interference between the fragment states populated through the successive hydrogen collisions. Classical H fragment distributions are found to be unstructured, which provides a confirmation that the above structure is produced by quantum interference effects. At least part of the structure is intense enough as to be observed experimentally. The mechanism of total fragmentation of the cluster is analyzed and discussed.