Blower Motor regulator
 

I have a 93 300se, blower motor works intermitantly,
I tested the voltage at the blower regulator terminals, and it was 12+volts. I then tested the blower motor at its terminals and the voltage was zero. Does this mean that the regulator is shot?
I have tested the PBC unit and it is putting out power. Other then the blower regulator,could anything else be causing the problem with the motor not working.

Not sure about on the 126, but on the 124, it's basically:

PBC
fuse
regulator
motor

On the 124, the regulator has three inputs (well, really just two): 12v power, ground, and control voltage. It steps the current up and down depending upon the control signal. So there should be a power line (constant V) and a control line (variable V, depends on PBC signal). If the inputs are working the way they should, but the output is zero all the time, then the regulator is probably bad.

Re: Blower Motor regulator
 

Join the club. Fortunately, mine only acts up when the A/C is on
(temp sensitive problem?) and even then, it works OK most of
the time, so I've ignored it so far.

Can someone tell me where the regulator is located? I spotted
the blower motor below the dust filter (passenger side, engine
compartment). It looks like you need arms as long as a gorilla
to reach the blower motor from the top of the engine
compartment, unless I'm missing something.

I would guess we are talking a 140 car.

The regulator is on top of the blower which is easily accessible by removing the big plastic cover (held by lage philips screws) rear right side of engine compartment. Just fold the cover over and leave all the vacuum lines attached.

The regulator controls the ground side of the motor in response to a 1-6v signal from the PBC.