MY JEEP 2000 GRAND CHEROKEE SUDDENLY WILL PRODUCE NO HEAT, THIS IS A SAFETY CONCERN SINCE THE WINDOWS WILL NOT DEFOG AND CAN CREATE SERIOUS VISIBILITY PROBLEMS. THE HEATING SYSTEM WILL ONLY BLOW COLD AIR, WHICH CAN SUDDENLY CREATE CONDENSATION ON THE WINDOW AND ENTIRELY OBSCURE VISIBILITY. THERE WERE NO EVENTS LEADING UP TO THE FAILURE, IT JUST STOPPED WORKING. UPON A SHORT BIT OF RESEARCH, IT SEEMS TO BE A VERY COMMON PROBLEM WITH JEEP GRAND CHEROKEE'S FROM 2000-2004 AND JEEP WILL NOT ACKNOWLEDGE IT AS A MANUFACTURING DEFECT EVEN THOUGH THOUSANDS UPON THOUSANDS ARE HAVING THIS SAME SAFETY PROBLEM HAPPEN TO THEM. *TR