DT:CONSUMER REPLACED FAN MOTOR TWICE BEFORE INCIDENT. CONSUMER WAS TRAVELING SOUTH ON STATE ROAD 441 WHEN SMOKE CAME INTO CAB FROM VENTS. CONSUMER PULLED OVER AND FOUND THAT THERE WAS A FIRE UNDER HOOD. CONSUMER WAS ABLE TO PUT FIRE OUT WITH HELP FROM AN OFF DUTY FIREMAN. THE FIRE SPREAD TO INSIDE THE CAB. CONSUMER KEPT THE FAN HOUSING WHICH HAD BURNED INTO THE FIREWALL. FIRE INSPECTOR TOLD CONSUMER THAT THE FAN MOTOR STARTED FIRE. VEHICLE WAS TOTALED. *AK