Engine and engine cooling: cooling system: fan
- Component
- Engine and engine cooling: cooling system: fan
- Manufacturer
- FREIGHTLINER CORPORATION
- Vehicles affected
- 27,500
- Reported to NHTSA
- 1996-11-13
- Owners notified
- 1997-02-11
Defect description
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.
Safety 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.
Manufacturer remedy
DEALERS WILL REPLACE THE FAN CLUTCH DRIVE DISC WITH ONE THAT INCORPORATES A THERMALLY ACTIVATED PRESSURE RELIEF.