In this study, a parallel flow condenser and laminated evaporator for an automotive air-conditioning system were modified to improve performance. Gas-liquid separation type condensers, in which the condenser and receiver drier are integrated, and one-tank laminated type evaporators were developed, and their performances were investigated experimentally using HFC-134a. Heat transfer characteristics in the condenser are examined by means of air temperature, air velocity entering the condenser and inlet pressure of the refrigerant; heat transfer characteristics in the evaporator are examined by means of air temperature, relative humidity, flow rate of air, outlet pressure of refrigerant and superheat. Pressure drops for both evaporator and condenser are also measured, and correlations for pressure drop are derived for the condenser and evaporator, respectively. Air velocity and mass flow rate of the refrigerant have a significant effect on the overall heat transfer coefficient, and flow pass is not significantly influenced by the cooling capacity of the condenser. The overall heat transfer coefficient of the evaporator increases as air flow rate, air temperature and relative humidity increases.