aux fan suddenly not working

[toki]

What happened was a fuse blew causing the blower motor to stop. Replaced blown fuse, blower blows again, all is well, right? Wrong, the aux fan now does not come on when the AC is on (or at all since then.) I have checked every fuse in the engine bay fuse box (also where the blower fuse popped) and can't find another blown fuse.

Is there a relay I should check or another area of fuses?

Thanks,
Ryan

[M5W]

In my M5 my fan will turn off suddenly when the ac is one. When i switch it to full it blows and then if i turn it back to 2 or 1 it works. Im searching for my problem to. If i find anything i'l let you know.

[seech]

Aux fan fuses should be no. 25 and 29 (if I remember correctly) in the fuse box located on left side of car in engine bay. The relay for aux fan is located in the box in front of the main fuse box (at least that's what it says in the Bentley manual. My E34 in Malaysia doesn't have that additional box but relay is in the main fuse box.).

You can also try to disconnect the fan switch located on the RHS of the rad. The connector has three holes. One earth, one for low speed and one for high speed. Take a wire and stick it into the earth and then low/high speed to test if fan actually runs on both low/high speed. If not the resistor is probably not working. Resistor is located in the aux fan housing.

How do I know all this? I've been having plentyyyyyyy....... of cooling issues of late so have become quite familiar with all the components.

Hope this helps.

[Mr 535i]

Check the resistor, is right on the aux fan you can look at it from the front valance. Check the Bentley Pg# 170-4 the complete check list is there.

[toki]

Another question -

The car still has those old ass I presume factory fuses in most places (including 25 and 29) that have a filament running across the open top. Is it possible for those to go bad without visual symptoms? I have just never seen those types of fuses before.

[Qsilver7]

I'm with Mr 535i (reply #4)...have you checked the aux fan's resistor...it's notorious ... BMW even sells a resistor repair kit (see #6 in the parts database & the diagram below): http://bmwfans.info/original/E34/Lim/535i-M30/USA/L/A/1991/01/mg-64/ill-64_0132/

http://bmwfans.info/original/images/8630_p.png

[GCR]

If the resistor is bad, the fan will draw enough amps when it gets a high speed signal to blow the fuse. It doesn't draw near as much if its already running on low speed and it goes to high speed.

[seech]

Just wire up the high speed and low speed fan switch to earth as mentioned before to confirm if it is indeed the resistor. Better to check a simple thing like that before dismantling the front of the car to get to the fan resistor.

Can't post URL so google "Gale's Repair Page" and check out the auxiliary fan page for details on what I'm talking about.