When a single-phase dual-capacitor induction motor refuses to start, begin diagnosis by listening: a loud hum suggests locked rotor or failed start circuit, while no sound indicates an open thermal overload or supply fault. First, check voltage at the motor terminals under load; anything below 200 V on a 230 V motor causes high current and torque loss. Next, de-energize and discharge capacitors safely with a 20 kΩ resistor; test microfarad values with an LCR meter. A start capacitor reading 20 % below rating or any visible deformation warrants replacement. Inspect the centrifugal switch: look for burned contacts, weak springs, or accumulated sawdust that prevents closure at standstill. Measure resistance across the auxiliary winding; infinite ohms indicates an open, while low resistance to ground signals insulation failure. If the motor starts but overheats, the run capacitor may be underrated, causing elliptical rather than circular rotating fields. Swap in a known-good capacitor and monitor current balance between windings with a clamp meter; deviation above 10 % points to turn-to-turn shorts. Vibration and noise often stem from dried bearings; listen for squeals or grinding, and replace sealed bearings using a puller and induction heater. Finally, test the thermal protector by running the motor under slight overload until it trips; the device should reset within five minutes once cooled. Document findings on a laminated troubleshooting chart inside the control box to speed future diagnostics for maintenance staff.