Originally Posted by
EAD15
The voltage regulator is part of the alternator. The blower motor doesn't have one.
You could check the system voltage in your driveway by using a multimeter on the battery and having someone sit in the car and hold various RPM. Only reason I suggested the drive logging method as I had a regulator failing that didn't show up except when the car was on the highway, but YMMV.
Edit: As for affecting other electrical items it probably would (that's why I think it's a long shot), but I've also learned electrical problems can manifest in strange ways.