SAFETY PRECAUTION: before doing any work on any electrical components. Make sure all power is off completely, it could be fed by more than one breaker or fuse. Discharge the capacitor. They can shock you as well as ruin your volt-ohm meter. Purchase a 20,000-ohm, 2-watt resistor (about one dollar). Connect the resistor leads to the capacitor terminals to discharge it. If your capacitor has three terminals, work your way around making sure you have connected one terminal to the other two with the resistor leads till all three have been discharged to the other two.
Oil Plugs
Motor failure usually consists of two types. Mechanical or electrical, sometimes one leading to the other. The first we'll cover is mechanical. this is usually the easiest to diagnose. For instance, if you can hear the motor making a squealing noise you no the bearings are going bad. Spin the shaft on the motor. If it does not spin freely the bearings are bad. If your motor has oil holes you can try to oil it. The oil holes are the yellow plugs in the picture above, remove them to oil and then reinstall them. Most times the bearings are already scored and the motor will need replaced. Note: always install a new capacitor when replacing any motor that uses one.
Testing Motor Windings
Electrical motor troubleshooting is a little more complex. You will need to shut off the power and unwire the motor leads, refer to the safety precaution above. Set your volt ohm meter on the ohm scale. You should read continuity through the motor wires, from one wire to the other. Fasten one lead to the common motor wire (the wires should be marked on the schematic affixed to the motor) touch the other to one of the other motor wires (I.e. one of the speed wires.) you should read continuity. Repeat this for all the wires till you have tested each one with the others. If the common wire was the only wire that would not read continuity, the motor has gotten hot and should reset itself after cooling off. If any of the other wires were open (did not read continuity) the motor windings are burnt into, and the motor will have to be replaced. If the motor spins freely but will not start spinning on its own. The capacitor is probably bad. If the top of the capacitor is bubbled up it has opened and will need replaced.
