Air Compressor Capacitor Wiring

Disconnect the power to the air compressor. The capacitor typically is located on top of the motor or at the back end. The cover normally is held in place with screws or nuts. Remove the capacitor cover to expose the capacitor and its wiring.

Touch both terminals of the capacitor simultaneously with a screwdriver to discharge any electricity still in the capacitor. Pull up the capacitor. Typically, it will be connected to the motor with a black wire and a white wire, but other colors may be used. One terminal will be marked to distinguish it from the other.

Write down or sketch which wire goes to which terminal on the capacitor. Alternatively, look on the motor casing or capacitor cover for a wiring diagram that tells you which color wire goes to what terminal. Disconnect and remove the existing capacitor

Buy a capacitor that matches the existing one. The capacitor should bear a label stating its capacitance value in MFD, operating voltage, cycles in Hz and temperature range. It should also bear the maker’s name and a capacitor number. Match either the specifications or the capacitor number of the new capacitor to that of the existing capacitor. Check that the new unit fits in the motor.

Connect the new capacitor to the motor. Follow your own wiring description or the motor’s wiring diagram to connect each wire to the correct terminal. Reinstall the capacitor and the capacitor cover. Try to start the motor. If the previous capacitor was faulty, the motor should run.