On the 400E/500E's the blower-regulator connector is in the same area as the 6-cyliner W124's.

However, with all the added vaccuum lines and fuse-holders it is hard to see.

I had to remove the driver's side/left lower-windshield trim, as well as the the water-channel in order to get good access.

BTW: here's another descripton of the test from another list:

>You can check the power and control signal to the blower at a plug
>located above and behind the brake booster. It has 3 wires, black, red and
>yellow.
>
>With the plug in the socket and the climate control on, check to see
>that you have +12volts on the red, a good ground on the
>black and 3 to 10 volts on the yellow.
>
>If the yellow wire voltage is a problem that points to a problem with
>the control module.
>
>If these all check out then the problem is with the blower control
>module or the blower itself.
>
>
>Doug Quance
>87 300TDT member MBCA