I have the W124 Service CD's and the W124 paper manuals, but can't find the test procedures to find out why the HVAC blower on our 1993 500E is not working.

I've checked all the fuses for continuity, and wiggled the ignition lock, but nothing.

Thanks in advance,
:-) neil
1988 360TE AMG
1993 500E

PS: to blower just stopped working one day

Go to the wiring diagram and you will see a three wire connector that is on the firewall. That connector has the 0-6v fan speed signal from the PBC (pushbutton controller) to the blower regulator and it has the battery voltage power wire that runs the blower. Pretty much the whole story.

If the battery volatge isn't there, look to the big fuse. If the voltage doesn't go up and down as you change the blower speed on the PBC on the speed input wire the problem is inside.

Otherwise the problem is the blower or the regulator. To verify which you will need to get to the blower as it is on top of the regulator and the first you get to. The blower regulator makes the ground side of the motor with the hot side always hot through that wire you checked. The regulator is like a end stage transistor. The 0-6v signal increases the flow to ground through the reg. This changes the speed.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Steve: I found the connector on my 1988 300TE (X64/ Blower regulator connector: 3-pole), but I can't find it on my 1993 500E.

Interior/Exterior?
Drivers' or Passenger side?
Near what major component?

Thanks,
:-) neil

Well,its possible its not there on cars with fresh air filters and/or v8s. It is somewhere though as they are still basically the same.
Hopefully someone with a car will know.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

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

BTW: I had both a hair-line crack on the blower-regulator fuse and corroded contacts at connector X64.

All is working again.

:-) neil
1988 360TE AMG
1993 500E