My ac unit in the house works fine, but is no tblowing cold air... I went outside and heard a buzzing/hummimg sound. When I removed the top the fan rotates by hand. I tried reseting my ac circuit breaker but no luck. Do I have a bad fan? Is there something else I can do to troubleshoot? Please help... Ryan :(

If the fan motor is buzzing, but the motor does not start, it could be a bad capacitor. With the breaker off, follow the wires back from the motor. One should go to the main relay controlled by the house thermostat. Another one or 2 may go to a smaller relay controlled by a thermostat, and then back to the other pole of the main relay. A pair of them will go to a capacitor, a tall, oval cross section, metal can with 4 terminals on it. The other 2 wires on it will go to the compressor. DON'T touch the terminals without shorting them out with a plastic handled screwdriver. If you get a spark, that half of the capacitor is good. A good meter has a capacitor checker. Otherwise a cheap analog meter on the ohm scale will show conductivity at first, but quickly go the end of the ohm scale with good capacitor. A bad capacitor won't show anything. An electrical supply house or a HVAC dealer should have a new one. If the motor isn't doing anything at all, Check between the main relay and motor for opens.

I came across the niftiest gadget for trouble shooting, a voltage detector. There are several brands. I have a GB Instruments GVD-505A, less than $15 at Home Depot. Touch it to a hot wire, and the end glows red. Find the doodad that lights it on one side, and not the other, and you have the culprit.