Greetings, I am a "newbie" just found your site last weekend. Have been reading all I can every night, (wife is not very happy, she says all I do is play on computer! imagine that!!!)I have learned alot.Enough about me, here is my problem I have a 72 280se 4.5 the aux. fan does not come on, when I ground the 210 switch wire there are two relays that "click" they are located on the right front firewall in the engine compartment. There are three relays mounted in front of three small fuse boxes. Two are "flasher-can" style and one is a ice cube relay. The ice cube is in the middle of the other two. The ice cube and the inward "flasher-can" style both click when I ground the the 210 wire. The aux. fan has ground but no "hot". Is there a fuse I am missing somewhere? When I apply power directly to the fan wires it works fine. I would really appreciate any feedback anyone might have on this. Thanks Phill

Let me dust off the cobwebs a bit. I can't remember which fuse it was, but those cars had separate fuse boxes for all the options.

Too many cobwebs, had too get the book. The relay for aux fan should be one of the round relays near the EFI ECU inboard of right headlight. There is another relay (round on the firewall) that is called the separation relay (it separates the activities of aux fan and timing control). The fuse box is a single two fuse panel on the firewall. In the picture it sits at an angle.

The fans on the 108/109 bodies also had a hood switch to keep vital body parts from suddenly becoming engaged in a fan coming on. This switch (a white button) must be depressed for the fan to come on.

------------------
Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Thank you very much Steve, it is 5:45am here in CA, but as soon as I get to work I will check it out! I will let you know what I find this afternoon.

Steve, First I checked the small fuse box's on the firewall, there were 4 that each held two fuses, none were burnt but the were pretty corroded, so I cleaned terminals and replaced all fuses. Still no fan, at the EFI ECU there were two round relays, I switched them and fan started working! I ordered the relay from a local supplier ($18) Thank you very much!
PS Have you considered doing this for a living?
Happy Motoring, Phill

Ummm Phill:

I think if you will check Steve's profile (just click on the question mark above his post), that he IS doing this for a living.

Hopefully speaking for the reat of us, we are more than elated that Steve takes so much of his time to asnwer our questions. I, for one, am happy that his answers are thoughtful and complete, not just one-liners which raise more questions than they answered.

Thanks Steve, and how in the world do you have so much time to help us, while also giving time toyour Shop and your family? It must be time-consuming.......Andras

Andras, It was a joke, I realize that he is a profesional, it is my standard reply when someone does something in their field that impresses me. I have learned a tremendous amount in the last week, I am in the proccess of reading all the past posts and appreciate the time and friendliness of all!