Ok.

My regulator is dying. Fan would not start up after church or this morning. Fan did come on this evening but I smelled the semi conductor burning and it stopped working. As the fan speed reduced I thought I heard the fan rattling at low speeds.

I took a guess that the regulator has never been replaced and ordered a w140 one that I am planning to adapt to the original blower

But

Is the burn out of the regulator caused by the regulator getting old? The fan motor drawing too much current or both? Don't think brushes could cause it to draw too much current unless somehow the brushes are shorting against the housing.

Could it be the bearings or fan cage rubbing against something in the airbox.

Looking for ideas so I can get as much as possible before opening up the air box.

Thanks

__________________
My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory

I think I figured this out for my car. From reading here and testing the output from the PBU at the plug behind the brake booster. I verified that the output voltages going to the regulator were within spec according to the FSM and here, so the PBU is likely OK. I then jumped the ground contact(where the blue wire goes) to the battery negative, didn't touch the red, and then turned the ignition to acc2. Result was the Fan blew at high and that probably the regulator was bad. After reading here, that seems to be the definitive test to see whether its the fan or the regulator. I followed the Blower Motor removal Wiki to get to the blower and then posts here to that point.

PeachPartsWiki: Blower Motor Removal

It is sortof the chicken vs the egg on which part it is, so now my car is down while I try to source a regulator I have a W124 so yours maybe different.

Treetops

Had this fun on my old 124 too. I know the regulator needs to be replaced on the w210. The burnt silicon smell has to come from the regulator. I just don't want to destroy the new one if the fan is pulling to much of a load

__________________
My Daily : 96 E-300 Diesel with 195,000 miles
Retired: 92 300D 2.5 T 345K miles and for sale
Retired: 95 E320 157K miles and currently parked with blown engine

Both retired cars are for sale as is my w124 shop inventory