Yes, the way the AC fan (ventilation, not radiator) works is that there
are resistors (a pack for each fan motor) that reduce the voltage so as
to lower the fan speed. I believe the resistors are up next to the
fans. In otherwords, a real pain to get to.

However, go to the back driver side pillar and check the connectors
back there. In order to gain access to the resistors, you'd have to
take that panel off anyway.

However, if BOTH fans are behaving the same way, then you should check
the wiring  before the resistors, not the resistors.