It often looks somewhat like a dried coffee stain. This taxes the capacitor and ages it rather quickly. A damaged or burnt out capacitor may hold only a fraction of the energy needed for the motor if its capacitance is low. Summer makes the machine work double time.

The higher the capacitance of the capacitor the more energy it can store. If the container is cracked or leaking, it is bad. This is also why the capacitor tends to go bad right when you need cool air the most. The most common signs and symptoms of a bad AC capacitor include: AC not blowing cold air AC takes a while to start once you turn it on Humming sound coming from your air conditioner AC shuts off on its own AC won’t turn on Sometimes really bad caps can leak their electrolyte out of themselves too. Then you may see this brown crust around the capacitor, or perhaps on it. A bad motor capacitor may cause starting problems or could shut off the motor while running. By taking the capacitor's resistance, we can determine whether the capacitor is good or bad. In this image I have tried to photograph the slight bulge on the top of this bad capacitor. Well, bad caps typically have a domed, or swollen top. If it bulges at the top, the capacitor is defective. Motor capacitors store electrical energy for the motor to use. During peak summer months, the power company may raise or lower the line voltage that leads to your home. To do this test, We take the ohmmeter and place the probes across the leads of the capacitor. Test a Capacitor with an Ohmmeter of a Multimeter A very good test you can do is to check a capacitor with your multimeter set on the ohmmeter setting. If voltage varies, this can be a problem for the capacitor. Trained HVAC professionals may observe smoke coming from the capacitor, smell a burning odor or actually see fluid ooze out around the base of the capacitor.