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Car 1985 635CSi Euro Spec. Manual Trans. (12/4/1984)

Auxiliary fan does not operate, which means no A/C and it's in the 100's

What I've done...
1. Verified fan turns by hand and is free with no binding or scraping.
2. Verified all fuses are good.
3. Jumpered the normal speed fan coolant temperature wires - fan does not turn - Also verified wire colors are correct.
4. Jumpered the high speed fan coolant temperature wires - fan does not turn - Also verified wire colors are correct.
5. Pulled the normal speed relay and metered the relay socket pins 87 & 30 - Have 0 vdc
5a. Jumpered the same pins and fan does not turn with 0 vdc. Duh! (Insurance) - Fuse 17 is good
6. Pulled the high speed relay and metered 87 & 30 - Have 12 vdc
6a. Jumpered the same pins and fan does not turn with 12 vdc.

Conclusions (sort of):

By using a jumper on 87 & 30 on the high speed relay socket, if the fan was good, it should spin, correct? I have 12vdc.
I don't seem to have voltage across 87 & 30 on the normal speed relay socket - what do I do with that?
Have not tested the normal speed relay until I can get 12vdc to 87 & 30. Somebody please tell me how.
Have not tested the high speed relay. I will save that until the fan actually turns via jumper.

I don't know where to go next. I don't really want to replace the fan ($$$), if there is something else wrong, yet based on what I've tested so far, that seems to be at least one of the problems.

Oh, and I did do a search, but couldn't find anything conclusive, nor a decision tree type of diagnostic process to eliminate "Parts Throwing".

I'm tapped out in the idea department. All help, suggestions, laughter - anything at this point would be helpful.

Thanks to all

Mike

P.S. If it is the fan, how do you get to it, remove the whole front of the car?

the fan (which varies with year) is held by three bolts and will come out of the car downwards. You can create better access to the bolts most easily by removing the kidney grilles.

Some things to check

- continuity through the fan motor
- continuity through the low speed resistor (usually mounted on or near the fan)
- that the fan turns freely
- that the fuses for both fan relays are good
- that the receptacles in the fuse box for the relay pins have not been pushed downwards, out of reach

My advice is if the fan is basically OK but you cannot get the thing to work easily, fit an separate relay (with a direct fused feed from the battery) to the outside of the fuse box and run wires to a manual switch on the dashboard if you cannot use any of the extant switches. That will allow you to drive the car and use the AC whilst you troubleshoot the OE wiring.

IME the early fan (a five-blade bosch one) is far more reliable than the later style of fan (with many curved blades), even though the latter looks like a proper job. I have had multiple examples of the second sort of fan fail, mostly by the magnets coming unstuck inside the motor. When this happens the fan is stiff to turn and the low speed resistor soon fails.

cheers

As usual, Brucey has very good points, but I would check the little fuse block that is exclusive for the aux fan

I'm not sure where in the grand scheme of things the fuse block is electrically speaking versus the relays, but I'm guessing it's before

This photo is from an earlier car so the location will likely be different, but I've seen these things disconnected, smashed in half, or worse, not even there

Wrong time not to have A/C

On my M6, that fuse block lives above the fuse box, on the other side of the strut tower.

I didn't see that you disconnected the motor, and verified the fan itself works by putting 12V directly into to. If there is a resistor mounted on the fan as well, check voltage before/after the resistor.

If you are not a stickler for originality, you could do what I did. Dump the original motor, and put in a modern, high speed unit. I put on a Dayton and it is AWESOME. However, you need to re-wire so that the low and/or high speed circuit ground the motor, and then you run it directly from the battery with a high powered fuse at the battery end. Once installed, it is powerful and reliable.

Jose

GRNSHRK wrote: ↑Wed Jul 11, 2018 9:29 pm As usual, Brucey has very good points, but I would check the little fuse block that is exclusive for the aux fan I'm not sure where in the grand scheme of things the fuse block is electrically speaking versus the relays, but I'm guessing it's before This photo is from an earlier car so the location will likely be different, but I've seen these things disconnected, smashed in half, or worse, not even there Wrong time not to have A/C

Bobbo I got me one of them little weird fuse blocks and for some unknown reason figured it had to to do with my add on a/c system. As I think about it I guess it does. I just haven't traced it out yet as we are close to getting the car running and then on to the auxiliary stuff. I was even lucky enough to buy a nice new one of those little guys many moons ago when the madness started

Hiya Bert,

It would be interesting to hear how the add-on system works, once you get the car running and start sorting the details

My guess is that the aux fan system will be the same as a US car with factory installed A/C, which would therefore incorporate the dual fuse block to protect those circuits

Still waiting to hear back from Mike

Did some ETK digging because I could not find the "extra" fuse block anywhere. According to the ETK, based on my VIN, it was never installed and what's even weirder, in Part Use, it says it wasn't fitted to 635's st all, just 633's and earlier. Yet, I vaguely remember seeing one on (I think) my US 635. Weird...

New issue:
Trying to remove the grills, where the headlights are so I can diagnose the original fan issue. Removed 4 screws and tried to gently pull it out, not happening. Seemed to be hung up on the corner light, so removed that. Still not happening.
I'm afraid to really yank on it as it's a Euro and don't want to replace any of that.
What am I missing? Is there some BMW magic I'm not aware of?
Help!🤪

The grills are also still attached from the inside of the engine compartment, on the backside of the side indicators/corner lights if I recall well.

Finally got the grills and kidneys out and low and behold found the connector for the auxiliary fan just dangling. Plugged it in, started the car, fired up the A/C and HOORAY, it worked. Think the A/C needs a bit of a charge, but I now have an auxiliary fan, so I don't need to stress about an overheat.

Have no idea why it was left unplugged, other than the car as been sitting for 4 years while being worked on by PO, so maybe just forgot.

Grateful to everyone here. You guys are the best!

Thanks again,
Mike