[crashoverride]

This is going to sound weird and counterintuitive, but I had the same problem it turns out the dealership put a weak battery with the wrong rating and after a few years it started to give out the car protected itself by NOT sending electricity to the blower. Once the battery was swapped out the blower hasn't had a problem. Another symptom would be the rear defrosters not working till the battery was better charged going down the road.
Check the battery an easy way is to pull up the hidden menus on the dash between speed meters.

I replaced the regulator a few times as that can also have similar symptoms. But never fixed anything and was a waste of time and effort

I say it's a weird symptom as we have all been brought up to believe if the engine is spinning the alternator is making electricity. But alas these smart computers make sure the electricity goes to keep the car going first. Then powers the accessories.