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Can some one explain how to test "jumper" my aux cooling fan? I read the Bentley and would like it simply explained to me, to test for function. I have had my e28 (87) for about two years now and cant ever remember it being on!? im an egghead i know. just want instructions in laymens terms. thanks. D.

I can't tell you how to jump it but if the car is all "stock" pushing the snowflake button (engaging the A/C) should cause it to turn on.
That tells you whether it is functional or not but does not indicate that the two sensors in your radiator are serving their function.

Oh forgot to mention my airconditioning is shot. that is another matter. I have had a fanmotor i bought months ago to get the ac going. but the ac doesnt power up at all.

Locate the temperature switches on the radiator. Now unplug them and jump the wires. You should hear it come on and quickly identify the low and high speed. If only one of them makes it work it could be the resistor that needs replacing (low speed).

Hi and thanks, once again-when u say "jump" does that mean to wire it to a 12v source or does that mean to touch the wires together? Just want to be certain before i burn something out.

take a short piece of wire and connect it between the two (make a small U shape).

jimoreno wrote:take a short piece of wire and connect it between the two (make a small U shape).

+1

Just connect the wires together on either the red (high) or other switch(low).

My fax doesn't work with the AC for some reason, but I jumped it and it started running. I just ran wiring and a switch inside my car so at the push of a button I can turn on the aux fan. The nice thing about this is when jumped, it still goes through the relay box. If it doesn't turn on when jumped, you know the relay may be bad.

tschultz wrote:

jimoreno wrote:take a short piece of wire and connect it between the two (make a small U shape).

+1

Just connect the wires together on either the red (high) or other switch(low).

My fax doesn't work with the AC for some reason, but I jumped it and it started running. I just ran wiring and a switch inside my car so at the push of a button I can turn on the aux fan. The nice thing about this is when jumped, it still goes through the relay box. If it doesn't turn on when jumped, you know the relay may be bad.

there is a diode between the AC switch and the normal (low speed). power. IIRC it is in the fuse box. That was the final fix on the Borman6's aux fan troubles.

Ok i tried jumping the fan, not sure if i did it right, i tried the two set of wires on the radiator, to no avail with and without the ignition swithch on, i also removed the cover which exposes the aux fan and jumped the switch/resistor that is mounted on the fan housing the upper and the lower switches, again with and without the ignition switches on-nothing. anything else i can do before i call the relay bad? Not a super biggie at the moment, the car runs fine and my ac is not working either, just want it to work when/if i need it too! Help?

It's two different relays, one for high speed and one for low, so I doubt both relays are bad. Start at the beginning, have you checked the fuse? And the fuseholder? That is one of the ones that likes to melt. Make sure you have power to the relays first, then go from there.

Is it the same fuse that burns out from the ac fan/blower? It (the fuse) burns out when i turn on the ac, i believe i got a stuck /inoperable fan motor