TRUCK IS A 2004 GMC REG CAB WITH 18k THIS IS THE FIRST SUMMER AFTER 2005 ELECTRIC FANS AND BIGGER RADIATOR. CONTROLED THRU HP TUNERS WITH NELSON HARNESS. NO OTHER TUNING HAS BEEN DONE ALL STOCK. DALLAS TODAY WAS 98 AND YESTERDAY NOT MUCH DIFFERENT. ONLY HAPPENS FOR ABOUT 2 TO 3 MILES AT MOST. AC BLOWS PRETTY COLD WHEN YOU ARE MOVING BUT AT IDLE OR AT A STOP LIGHT BLOWS HOT. TRUCK DOES HAVE FACTORY ALTERNATOR. VOLTAGE DROPS WHEN ELCECTRIC FANS COME ON. ANY IDEAS?