The 3A fuse on my circuit board keeps on blowing. After I replace the fuse, the evaporator coil blower will run just fine, but, when I try to turn on the A/C, the fuse blows, everything shuts down and then nothing comes on. I'm guessing the relay inside the condensing unit is probably shorting out. Does this sound reasonable? Can I test the relay to see if it is faulty?

Look at the windings on Contactor for discoloration or burnt. For a quick test remove both wires from contactor coil, insulate, turn to cool. If it still blows, short may be in control wiring, also, try Fan only, to make sure not blower relay/contactor not shorted.

What may be more likely, is a dog cewed the tstat line outside. Inspect.

Pulled the 24v wires off the outside unit and it didn't trip when on "cool". I replaced the contactor even though it didn't look burnt and unit is only 18 months old. Condenser fired right up without blowing the fuse! Works fine now. Thanks.

Good Deal.