... detection 4. Emergency switch 5. Mini frequency conversion Dongguan VKOOL Hot Research Technology, V018 mini WOOD portable car refrigerator,car freezer ... every 4 S issued two fault signal.B, compressor start mistake, compressor control box every 4 S issued three fault signal ... every 4 S issued four fault signal.D, compressor overheating protection, compressor control box every 4 S five a fault signal ...