What are you using in the socket? The cigar lighter, cell phone charger or something else? Phone chargers are notorious for blowing fuses, if it's the cigar lighter, check it with a known good one, same with the phone charger. If all else fails, look inside the socket for loose metal parts shorting the socket. If the fuse only blows when plugging something in the socket I would have to say, the problem exist in the accessory. Let me know.