The carbon vacancy (V C) is the major charge carrier lifetime limiting-defect in 4H-SiC epitaxial layers and it is readily formed during elevated heat treatments. Here we describe two ways for controlling the V C concentration in 4H-SiC epi-layer using different annealing procedures. One set of samples was subjected to high temperature processing at 1950 C for 3 min, but then different cooling rates were applied. A significant reduction of the V C concentration was demonstrated by the slow cooling rate. In addition, elimination of the V C’s was also established by annealing a sample, containing high V C concentration, at 1500 C for a sufficiently long time. Both procedures clearly demonstrate the need for maintaining thermodynamic equilibrium during cooling.