Some of these cars were retrofitted with 2 15 amp fuses outside the main fuse box. I don't remember if those fuses are for the ACC system or just the blower.

Was there axial play in the blower motor? If so it could have worn bearing causing the brushes to slide off the contact areas. It'll work if you test it with the shaft horizontal but not if it's installed with the shaft vertical.

Does the blower come on if you kick the bottom of the blower housing?

Does the blower come on if you set the switches to defrost and max blower?

Does the compressor engage in defrost?

Sixto
95 S420
87 300SDL