Have an E320 1994 with dust filters. Blower was only working on low and now does not work at all. Have checked the ACC control unit in dash with the working one from my E420 and still nothing. Next took apart all the stuff that hides the blower motor and checked that, it runs just fine. Checked all the fuses including the ones outside the main fuse box, all replaced with new fuses. Now I think it is the Blower motor regulator and before I order a new one, I would like to know if I should check anything else that could cause the problem.
Thank you in advance for any advice.

Sounds like you need to replace the blower motor regulator.