United States 96V232000
FREIGHTLINER LLC
The problem
VEHICLE DESCRIPTION: HEAVY DUTY TRUCKS EQUIPPED WITH HORTON FAN DRIVES. THE FAN DRIVE CONTROL SYSTEM WAS RECONFIGURED WHICH RESULTED IN A SIGNIFICANT INCREASE IN THE DEMAND FOR FAN ACTIVATION AND ASSOCIATED STRESS TO ELECTRICAL AND MECHANICAL COMPONENTS. VARIOUS COMPONENT FAILURE MODELS, COMBINED WITH CHARACTERISTICS OF THE FAN CLUTCH AND ITS BEARINGS, CAN CAUSE FAN CLUTCH BEARINGS TO FAIL PREMATURELY AND RESULT IN A LOCKED FAN.
Risk
IF THE FAN IS LOCKED, THE THE SYSTEM CALLS FOR THE FAN TO BE ON, THE FAN CLUTCH WILL SLIP, GENERATE HEAT, AND UNLESS RELEASED, WILL RESULT IN A FIRE.
What owners should do
DEALERS WILL REPLACE THE FAN CLUTCH DRIVE DISC WITH ONE THAT INCORPORATES A THERMALLY ACTIVATED PRESSURE RELIEF.
Units 27500