connecting to 220 will also blow those fuses, but usually, even tho the fuses blow, the converter will still be fried. As to why? I have no idea. If it worked at the Dealer and then YOU plugged in at home, that points to YOU having a 120 power supply problem. Years ago we sold a 30 amp Airstream Land Yacht Motorhome and everything worked great at delivery on shore and Genset. They went straight home to their Dairy Farm and then called us complaining that a lot of their appliances did not work at their Farm. It turned out they connected to 220 Plug in their large work barn. So, things happen that are not a dealers or OEM's fault. My take on these type things is simple. IF it worked as designed at delivery and then you call back in a few days with a major problem, odds are YOU caused it. But, people will argue this point and never own up to it. Doug