As of today i am new to the forum (lots of great information on here) I bought my first jeep just over a year ago and have loved every minute of it. Its a 2000 XJ with 120,000. I am now having a problem when i have the heat on, when the heat is on it discharges to around 12-13, but when i turn it to either of the defrost settings it discharges nearly all the way and says check gauges, my headlights dim, and the stock stereo turns off display and all. It will do this off and on. The only way to get it to quit is to turn the heater all the way off. Its been doing this about a month and has killed my battery. My only suspect is maybe the blower motor is bad and is drawing too much power? When a bought it i replaced the serpentine belt with a Gatorback and it is on there very tight so i don't think its slipping. Any help would be much appreciated.