... frequency conversion Dongguan VKOOL Hot Research Technology, V018 mini WOOD portable car refrigerator,car freezer,Car Fridge, car cooler, car cooler ... every 4 S issued two fault signal.B, compressor start mistake, compressor control box every 4 S issued three fault signal ... box every 4 S issued four fault signal.D, compressor overheating protection, compressor control box every 4 S five a fault signal ...