Robc1977

There was only three wires a white black and bare wire

I was running my RV off 20 amp and using a plug to run window unit and seemed to do just fine and all outlets were working good. The A/C won't kick on with 20 amp but makes buzzing sound. I flipped breaker for A/C and just didn't use it. My step dad wired a 3 prong 30 amp plug so I could use 30 amp. I plugged it in and it started smoking out of the converter box . Someone please help. I don't know what happened or what to do. I hope I can fix this issue cheap hopefully I didn't damage something.