Which of the following testing methods can indicate a capacitor issue in a single-phase motor?

Using a multimeter to measure capacitance is the most effective method to indicate a capacitor issue in a single-phase motor. This method allows you to directly assess the actual capacitance value of the capacitor compared to its rated value. If the measurement indicates that the capacitance is significantly lower than specified or that the capacitor is open or shorted, it confirms a fault in the capacitor.

Other methods, while potentially useful in diagnosing motor issues, do not provide specific insights into the condition of the capacitor itself. Observing the sound of the motor might reveal operational issues, but it cannot pinpoint electrical faults or component failures like that of the capacitor. Inspecting the wiring connections helps ensure that there are no loose or damaged wires that could affect motor performance but does not directly test the capacitor functionality. Similarly, checking for physical damage on the motor body may indicate surface issues but would not reveal any internal capacitor problems. Thus, measuring capacitance directly with a multimeter is the most reliable approach for identifying capacitor issues.