I had a customer coming with the same issue. I sold him a regulator and he said it's working fine now. To replace the regulator the cabin blower needs removed as well as the lower cover with two torx. You may be better to replace the whole blower with a new aftermarket unit at this point, even with ...

Only three things it could be ... Fan Control Module, Climate Control Module (CCM) or wiring from FCM to CCM.