We have analyzed the hysteretic properties of thermal and pressure induced low spin (LS)虠high spin (HS) phase transition of a 3-D spin crossover (SCO) nanostructure when the cluster architecture is progressively changed from a cubic to a thin film. For solving the 3-D Ising-like Hamiltonian, the Monte Carlo metropolis technique is used, with the edge molecules trapped in HS state. The role of short- and long-range interactions on the SCO cooperativity has been investigated as well. The obtained results show that the cooperativity of a 3-D SCO system, characterized by the same number of molecules and the same interactions strength are strongly affected when going from a cubic 3-D to thin-film architecture. These results are discussed in terms of surface effects.