300SDL Auxiliary Fan Problem

[Terence Lowe]

The auxiliary fan on my 300SDL never seems to work. I've searched the various forums but haven't found an answer yet.

The auxiliary fan works fine when I jumper the load side of the auxiliary fan relay. The temperature switch for high-speed operation also appears to work. According to the wiring diagram the wire between the temperature switch and the relay should be brown/green. However, at the temperature switch it is brown/green, but at the relay there is a brown/white (or maybe brown/gray) wire on the coil contact. Testing the circuit from the temperature switch to this contact appears to show an open circuit (which explains why the fan doesn't come on).

Does anyone know where the brown/white wire comes from? My car has the automatic climate control system, so I wonder if that brown/green wire goes to that and then mysteriously changes colour to brown/white en route to the relay?

Would it be safe to connect another wire directly from the temperature switch to the relay coil contact?

Thanks

Terence Lowe