I have an outdoor Lennox HS29-411-3P. When the A/C kicks on, the unit hums but the outside fan is not spinning. There are 3 wires coming from the fan. The orange and black go to a black piece that the incoming 120V come in to. The purple wire goes to a capacitor. Is there any voltages I can check on capacitor or any wires to connect to see what is working and what needs replaced? Any help is appreciated.