If it is melting on startup you have the polarity wrong. The torch goes in the negative. Also in AC you need about 30-40% balance only. This isn't a miller which is backwards from ours on AC balance adjustment.(cleaning) You should see a cone, and you should be using the red 2% if you have it for aluminum...but yes in AC you'll get a cone. You don't see a lightning bolt on an inverter because there is no HF overlay.