WE DETECTED A BURNT RUBBER SMELL WHILE DRIVING ON A SURFACE STREET (WITH A/C ON). THE A/C SUDDENLY QUIT. WE PULLED OVER TO TURN SUV OFF AND BACK ON AGAIN HOPING A/C WOULD RETURN. A/C DID NOT RETURN, SMOKE BEGAN BILLOWING OUT OF A/C VENTS. STOPPED AT A GAS STATION AND TURNED OFF SUV. THE SMOKE FROM THE VENTS GOT THICKER AND LARGE FLAMES BEGAN COMING OUT UNDERNEATH THE DASH. HUSBAND RAN IN TO GAS STATION AND GOT A FIRE EXTINGUISHER AND PUT OUT THE FIRE. FIRE KEPT RESTARTING (THE PARKING LIGHTS WERE ON THOUGH THE CAR WAS OFF). HUSBAND FINALLY HAD TO DISCONNECT THE BATTERY TO KEEP FIRE FROM RESTARTING. THE A/C/HEATER BLOWER THEN FELL OUT ONTO THE FRONT PASSENGER FLOOR-MAT BURNED TO A CRISP.