The purpose of this study is to analyze the effects of surface defects (e.g., notches) and external environment conditions (e.g., operating temperature, the number of re-welding) on the static strength and fatigue of Al3003-O aluminum tubes used in the heat exchangers of air conditioners. In this study by the aluminum tubes to perform fatigue tests on the actual tube product and then the fatigue characteristics were evaluated using stress-life(S–N) curves. Regarding the welding conditions (maximum 600 °C and 10 s), the grain size grew and the hardness decreased as the number of re-welding increased. The effects of the operating temperatures on the fatigue life were examined at a room temperature of 25 °C and a heat exchanger operating temperature of 125 °C, resulting in the fatigue limit(57.19 MPa -> 49.02 MPa) at operating temperature was lower than room temperature. Furthermore, the fatigue limit of 29.37 MPa measured in the notched specimens (notch angle of 90 ˚, notch radius of 0.02 mm, and depth of 0.115 mm) was lower than that obtained from those without notches. The material constant (0.03) used in the Peterson equation was then computed from the fatigue notch factor (1.67 = 49.02/29.37) and the stress concentration factor (2.73) of the notched tube specimens was obtained from the structural analysis. This material constant can be used to predict a decrease in the fatigue limit over varying notch sizes in aluminum tubes (Al3003-O).