15 years installing car audio and I have never seen that....learn something new everyday. I will venture say though that if the wires melted the voice coil is shot also and the speaker is a paper weight. What I would be concerned about it what caused the melt down. I do not think AC could do that....could be wrong......but I would think your amp was sending DC to the speaker. I would use a mulitmeter on that speakers output on the amp. Also check the wires for a dead short.