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I've been wrestling for years to keep my radiator fans working. Old motor rebuilds or replacing with used motors worked for me but I wanted a longer lasting solution after my last old motor started to fail. So I bought two new replacement motors, Bosch branded replacements, that work well when connected to 12v but fail to stay on when connected to the final stage driver. The driver will start the spin then shut down. The old motor turns on normally and continues to run. So after many circuit component changes I've come to the conclusion that the control unit and final stage work correctly. I noticed during rebuilds that the old motors have internal series inductors. I am not sure that the newer motors are built this way. So I removed the old inductors and externally added them to the power feed from the final stage to a new motor and the motor functions correctly. Conclusion: the new motors do not have the same inductance as the original thus causing the driver to fault the motor.
I do not want to use the un-elegant solution of series inductors and would like to modify the final stage to account for the different inductance of the new motors. Is there any electrical engineers in the forum that might be able to help? I have drawn up a schematic as accurately as possible because some component values are not known to me.
Any help is appreciated.