Just within the last week, my dash has developed a 'sound of light crackling, under the dash. It stops ( temporary when I change the vents direction, or change between internal or external ventilation. It dosent stop when I turn the air con unit off. It just keeps on crackling. Once, it kept happening after even removing the keys, but stopped when I locked the car. Sometimes, when I've driven it lately, there's no noise at all. Anybody come across this before........?