aux fan not working

[tosbt]

Started to run over 212 and I noticed that aux fan was not working to bring the heat down, checked fuse under dash but all looked ok. What should I look for? 300SEL 4.5.

[Tomguy]

tosbt, mine doesn't turn on at 212 either! Dunno why... but if I shut the car off at 175 and come back with it at 185, it'll be running!

I wired a manual switch back to under the dash - it just hangs there, but works well enough. All you have to do is hook it up to the ground on one end, and the wire at the temp sensor on the other. To test the fan circuit, take the wire off the temp sensor and hook it to ground with the ignition on (prefferably with the engine running - if the points happen to be closed and the engine off, you can burn up the ignition box!)

[psfred]

Ground the wire at the temp sensor. If the fan comes on, the sensor is bad, replace. If the fan does not come one, check the fuses in the little box. You may have to trace the wires down, I'm not sure where they are on the W109. Relay operates off the temp switch, closes the fan ciruit.

The fuses are in one of the little brown boxes under the hood, probably next to the window relay on the passenger fire wall.

You will also need to check the fan itself by wiring directly to the battery. If it's bad, the one off a W116 will drop right in, and it's bigger, too.

Peter

[tosbt]

Thanks for the reply guys, yes there are 8 fuses at the firewall behind the battey and I replaced them all. I think I have a loose connection at the fan however works when I shake the cord. We shall see.