I have a 1994 bmw 530i. When i us the a/c in the summer the fan will howl real loud.We have to turn the fan off and then back on, most times it will stop but sometimes it will do it again minutes later!it does not do it with the heat on
IIRC your BMW uses a different fan for heat and A/C. Your A/C fan has a bad bearing. Replacing the fan’s motor is recommended. It may come as a complete fan/motor unit.