This paper concerns the optimization of brazing conditions for joining the two dissimilar materials Oxygen-free high conductivity (OFHC) copper and ASTM A501 low carbon steel usually used for an Oil-Separator of an air-conditioner using Ag-based(BAg) alloy as a brazing filler metal (BFM). A mixture of 70% $N_2$ and 30% $H_2$ gases was used to prevent oxidation of the joints during furnace brazing process. Brazing joint clearance, length, temperature, and time were selected as design parameters that have significant effect on the bonding strength of a brazed joint. Taguchi method was used as a statistical technique for design of experiment (DOE) in an attempt to optimize brazing conditions in terms of shear strength. $L_9;(3^4)$ orthogonal array was designed for conducting the experiments. The relative influence of design parameters and their interaction on the response were also discussed. The experimental results verified that the brazing conditions predicted in this study by Taguchi method could produce the brazed joint between OFHC copper and ASTM A501 low carbon steel with maximum shear strength.