R170 Blower Motor - No Power

[gbjeppm]

HI All,

Hoping somebody has seen this before as it is driving me somewhat crazy.

A friend of mine has an R170 SLK320 from 2000, it has has a number of issues which i am steadily working through.

The final issue is that the blower motor/fan for the interior heat/AC does not work at any setting, The control panel behaves as expected, the EC. Recirculate and Rear Window lights all work as expected.

I took the blower motor out and tested it and the regulator on the bench, and all fine.

I then test for power at the incoming plug, which has 3 wires, 12v switched, Ground and Variable from the console switch between 1-5 for fan speed.
There is no power at the 12v switched with engine running, or ignition on or off for that matter, but i do get between 2 and 6.5 V at the variable wire as you would expect.

So that leads me to think fuse, but i have tested all of them multiple times and they are fine, and everything else on the car works.

So i am at head scratching mode. Any ideas welcome.

I have had issues with the K40 relay (no engine start and radiator fan running, i have fixed those by resoldering the relay), and i am now assuming there is no relation with the K40 and the interior blower, if somebody could confirm?

Also if somebody has access to WIS could you get me a wiring diagram for the heating/cooling system.

Thanks in advance

Matt

 

[BlackC55]

Are you sure the regulator is ok?

 

[gbjeppm]

Are you sure the regulator is ok?

I tested it on the bench by bridging 12v across two pins and ground on the other On the regulator and it worked fine.

I don’t have 12v in the red incoming wire that I Think I should have, but I do have variable voltage in the white/pink Wire

 

[gbjeppm]

Solved:

well fuse 36 was missing, hence no power.

so don’t assume all fuses are correct and in
the right place