1971 300SEL 3.5: aux fan not working

[werminghausen]

Originally Posted by Mike D

Found my pin out note on the relay.

Terminal #30 High power feed (needs to be fused)
Terminal #85 Relay ground (this is the one to connect to the 100C switch)
Terminal #86 Relay feed (ignition ON feed) (trigger wire)
Terminal #87 Output supply-normally open (used in 99.37% of applications)
(Terminal #87A Output supply-normally closed (rarely used))

I don't know how you would go about changing the newer style housing into the older round canister style. I don't think it can be done. I have shoe horned the newer styles into the elongated metal cans but it was a pain and I'd never do it again just for "originality".

So, the always "hot" wire goes to terminal #30, ground/earth/100C switch (use an ohmmeter to check continuity with the 100C wiring harness) terminal #85, ignition trigger wire (12V when ignition is on) terminal #86 and fan power feed terminal #87.

Thanks so much for this information,
I found my old cube relay (4 Terminals...from a Bimmer) and you are right, it won't fit into the canister/cylinder, doesn't make any sense to do ...so the repair will be visible , not original. So what? Main thing I can drive in the deserts.
Anyway I am about to finish all my radiator/block flushes and install the 'new' fan clutch with a shorter pin. See how all these parts will keep cooling at low temps.