Fan output stage repair

Radiator fan output stage repair

Fitted at the front of the engine bay this unit regulates the output to the radiator fans on S4 and later 928s.

A common failure condition is one of the dual fans running at full speed and the other remaining static, both not working or spinning as soon as the ignition is switched on.

These units employ logic comparison circuits and high power transistors that directly control the current supplied to the two radiator fans.  If this unit fails other checks of the system are required.

• Each fan has a fuse in the CE panel
• The fans are getting old, check for free rotation (battery earth strap removed first).  Bad bearings can create drag and require more current to drive the fan motors resulting in overload of the fuse and or power transistors in this unit.

JDSPorsche can repair and fully test the operation of these output units with a custom built test rig.