I've run into a bizarre problem with my climate control blower motor. I began noticing an intermittent squeeling noise that started very quietly and has progressed gradually to a constant irritating noise that sounds almost like a bad bearing. I am also noticing that the fan speed is beginning to vary. It doesn't do it all the time but only on occassion. So, as a short term fix while I ordered a new blower motor I took the old motor out and lubricated it. This didn't help in the least. When I got the new blower motor and installed it the problem still exists. The only other problem I could fathom would be a bad regulator. I haven't tested the voltage on it yet but plan to do so this evening. Could a bad regulator cause this squeeling sound?

I am not familiar with this model. But I have removed and inspected many blowers and related parts to the W201 and W126 chassis.
The noise you are hearing, IMHO, is not the regulator. No moving parts that I know of. If your car has one, the noise is coming from the aspirator(air sample blower). This small blower takes air samples from inside the car and blows them over a room temp sensor.
In the W201, the aspirator is located behind the passenger vent. In the W126, it is behind or under the glove box.
Over time, the blower get very dirty. The bearings dry out and thus the squeal. If you locate yours and remove it, test the fan blades. They should spin freely with very little effort. If not, apply a thin oil to the bearings and test with 12V. You may be able to recover.
I have a box full of these little blowers I sell on Ebay.
The pic attached is what you may be looking for.

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Thanks for your suggestion but the aspirator installed in the 2000 C 230 is located overhead in the light cluster. The noise I'm experiencing is coming from the under the glove box on the passenger side of the vehicle where the blower motor is.