I know typically this would mean that I have a heater core leak, or possibly some wires have fried. But when driving the 64 t bird to work today, I decided to turn on the heater. Thin white smoke started coming from the defroster and heater/air conditioner and I immediately turned it off. It only lasted maybe 5 seconds, and it did not come back. It did not smell like antifreeze or like wires burning. It did rain last night, is it possible it could just have been water being vaporised from that? I sure hope that's it lol