Alternators on PA39 are they the same ?

[ComBE]

[AlanBreen]

Alternators don't mind which they turn so will work when turning either way. However there is a cooling fan attached to the front of the alternator just behind the pulley. A different fan is required depending on rotation direction.

You may be able to take to fan off the old alternator to get the correct fan for the direction rotation.

With your original fault it seems to me that the alternator is working OK but is going to full output which tells me that you have a regulation problem.

You may want to check that the regulator is sensing the battery voltage correctly. If this wire is open circuit or is high resistance, the alternator will go to higher than required or full output.

Alan