Teminal 12 on the fan controller to power it up, and where is the source?

__________________
1984 280SEL, 62,000 miles
Euro model in the USA
1983 300D (Totaled out 10/2004)
New Factory Mint Green paint
Palomino int
1982 240D (Steak dinner for two)

Fuse 8.

Bad brushes would be making bad or no contact with the electic motor armature. I'm chasing the same issue with a contact switch or relay contact. Even the ends of a fuse can loose contact and quit delivering electrical current. Thats why I need a wiring schematic to follow the electrical current (Yellow Brick Road) back to the source.

I'd like to do this as I hate throwing money at guesses. (Good idea for an avtar or icon. Picture Yosemite Sam throwing money at his benz)

__________________
1984 280SEL, 62,000 miles
Euro model in the USA
1983 300D (Totaled out 10/2004)
New Factory Mint Green paint
Palomino int
1982 240D (Steak dinner for two)

Checking solder joints and cleaning relay contacts, as recommended, is a pretty low-cost evolution. It also has a very high probability of success.

While certainly possible, failure of the blower controller or the associated resistor unit is much less likely than a problem within the push button unit. Failed solder joints there, along with dirty relay contacts, are a very common occurrence.

Ok I think I'm thrilled now!

I relaced the fan controller from the one out of my donor car. All buttons work and have a fan function now, well except for the off button.

For those of you who tinker and tear stuff appart here's the pics.

There are relays in the fan controller box and the second one from the left I see where the contacts are pitted which could be the cause of the fan failure. In the second pic I see signs of a heating at a solder joint which may be a cold solder joint. Third pic is of the shell of the box so you can see where the snaps are (all sides) so you don't have tear yours up.

So bottom line we need a schematic to do further diognosis. I didn't take the time to check terminal 12, because I found a few terninal 12s

Attached Thumbnails

     

__________________
1984 280SEL, 62,000 miles
Euro model in the USA
1983 300D (Totaled out 10/2004)
New Factory Mint Green paint
Palomino int
1982 240D (Steak dinner for two)

The commonly available MB schematics are do not offer much detail for solid-state type components, other than terminal identification.