lewmer

I need information about the Power Stage between the ECC and the Heater/AC fan in my '93 850.  The original (1993) ECC failed was replaced with a newer version (9166550) a few years ago, which required some rewiring (271927).   I recently noticed that the fan is running much slower than the fan in my '96 850.  In my '93 850 with fan set for maximum speed, I measured 4 volts across output of power stage and 7 volts across fan motor.
Q1 - Should the fan go to full speed using the original '93 power stage and the newer ECC?
Q2 - If I replace the power stage what part number should it be?