VAN WAS BEING DRIVEN EARLY MORNING FOR ABOUT 30 MINUTES. NO RAIN, 45 DEGREE OUTSIDE TEMP., HEADLIGHTS ON. DRIVER FIRST NOTICED DASH LIGHTS FLICKER & ALTERNATOR GAUGE SHOWING A DISCHARGE, THEN THESE ISSUES RETURNED TO NORMAL. THE VAN CONTINUED BEING DRIVEN FOR 15 MINUTES TO DESTINATION W/O FURTHER ISSUES. UPON DEPARTING VAN, DRIVER NOTICED UNUSUAL SMELL AND WAS TOLD BY ANOTHER PERSON THAT SMOKE AND FIRE WERE COMING FROM UNDERNEATH THE VAN AT ABOUT MIDPOINT. UPON INSPECTION THE DRIVER SAW FLAMES EMANATING FROM SAID POINT UNDERNEATH THE VAN AND LIQUIDS ON THE GROUND. EMERGENCY CALL TO THE FIRE DEPARTMENT WAS MADE & A THIRD PERSON BROUGHT A FIRE EXTINGUISHER TO THE SCENE. FIRE WAS EXTINGUISHED BUT REIGNITED AS THE FIREMEN ARRIVED TO COMPLETE THE JOB. VEHICLE NOT SEVERELY DAMAGED AND NO INJURIES. VEHICLE WAS TOWED FOR INSPECTION. DISCOVERED THE ALTERNATOR CHARGING WIRE TO THE BATTERY HAD NOT ORIGINALLY BEEN SECURED OR SHIELDED PROPERLY AND WAS RUBBING ON A BOLT HEAD SECURING TWO A/C CHARGING TUBES. OVER AN EXTENDED TIME THE WIRES INSULATION WORE THROUGH & VOLTAGE WAS SUPPLIED TO THE A/C FREON TRANSFER TUBES RUNNING FROM THE LEFT FRONT SIDE TO THE REAR OF THE VAN WHERE THEY CROSSED OVER TO THE DRIVER SIDE AT ABOUT MIDPOINT ON THE BODY. THE CROSS TUBES ARE BETWEEN THE VEHICLES BODY & LONG SHIELD. THIS IS WHERE THE POSITIVELY CHARGED REAR A/C TRANSFER TUBES MADE CONTACT WITH THE NEGATIVE/GROUNDED REAR HEATER TRANSFER TUBES, SPARKED & IGNITED THE COMBUSTIBLE FLUIDS WITHIN THE FREON. T