This paper deals with the investigation of thermo-vibrational convection induced by harmonic vibrations of the temperature boundary conditions in a square cavity heated from bellow and containing a low Prandtl number fluid. The governing equations are solved by using a finite volumes method. Effects of thermal modulation on the all regimes occurring in the cavity when convection intensity increases are analyzed. A characteristic modulation frequency allowing the reduction of the average intensity of the flow and heat transfer at the cold wall has been identified. The effect of phase difference between hot and cold temperature is also studied.