Electric fan question

[Motorhole]

Ok, so today was the first time my car has run for any real length of time. Drove it round the compound, hot air from the heaters, virtually nadda from the bleed screw afterwards, all looks good as far as coolant is concerned.

However, I ran it up until the temp was just over the halfway mark and the electric fan still hadn't switched on.

I have an 80-deg thermostat and 88/90-deg 2-speed fan switch fitted - when would I expect roughly to see the fan coming on? Just wondering if either I've c*cked up the wiring somewhere or there's another issue...

[327ire]

When I'm installing stuff like that I try to test it before installing using a kettle. Just wire 2 cables onto the switching terminals, boil it and at some point you should read continuity on a multi meter.

[Motorhole]

Cheers bud. As a start I guess I should check whether or not the switch is hot to make sure there isn't an air pocket in the rad. Are there any other things to check before I pull the switch out to check that?

[DanThe]

Wrong switch, you need the 80/88 part number = 61 31 8 361 787

[jimbom30cab]

and when fitted my fan comes on at a nat's whisker past the 12 o'clock (so basically 12 o 'clock) It ALWAYS checks the temperature back down so the needle never goes past 12 position . (M30 engine but essentially the same set up i think)

i also fitted mine to the thermostat housing on the engine side of the thermostat

[Motorhole]

Cheers Dan. I will check my receipt to make sure I got that right, but you may be onto something

[DanThe]

Your switch is pretty good Jim, got a link mate? Its an 88 degree thermostat in your engine IIRC?

The temps are stamped into the side of the switch BTW

[Motorhole]

Okay, apologies my facts were wrong regarding my temp switch. This is actually what I have fitted:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 0710597992

[DanThe]

Jesus, thats dearer than the genuine BMW switches!
Cant see a part number listed either so could be anything, you will have to check the switch itself to be sure

[Motorhole]

Pretty certain I didn't pay that 2 months ago

Okay, will do tonight. Is it possible to short across the switch with a jumper to see if the fan works and whether or not the issue lies elsewhere? Also would this work at stage 1/2 ignition, i.e. without the engine running?

[Motorhole]

Right, switch is deffo 80/88 degree switch, stamped on side. Also, there's no air pocket in the radiator. Unscrewed switch and coolant dribbled straight out. Switch also got warm after running for a short time (though I didn't run for long enough to get fully up to temp this time).

As above, can I jump it to simulate the switch working and see if the fan comes on? Which wires to jump? This'll tell me if its the switch or whether my wiring is all to c*ck I guess.

[jimbom30cab]

Yes, with it all connected properly and the circuit energised and a relay fitted, simply put a screwdriver blade across the 2 contacts with the wires connected and it should wizz into life, or just join the connectors.

You can either wire them through the switched ignition so it is hot when in run or start. Or simply wire direct to the battery so it's hot all the time - the fan will then run after turning the car off which is handy for scaring cats off the bonnet.

There are loads of guides on the net how to wire these up and any spare 4 prong relay will do.

Alternatively Danthe on here produces an excellent plug and play proper fan loom which is good value and used the e30 fuse box for a proper oem install.

[jimbom30cab]

I think I bought this one iirc

http://www.cbsonline.co.uk/product/Fan_ ... _1.5_FANSW

[Motorhole]

Thanks jim,

Yeah, I'm already using one of DanThe's looms and I've wired it up as per his instructions, just slightly concerned I've mucked it up somewhere. Need to dig out the pics...anyway I have a 3-pin connector for the temp switch, so there are two 'speeds' and an earth I guess, just wondering what coloured wire does what.

[jimbom30cab]

Trial and error mate, worst you can do is blow the fuse

Just bridge the connectors

[DanThe]

Yep just bridge the pins, if you hold the plug with the cutout at the side, one pin on top two underneath, the top pin is live and the lower pins are the switch wires

[Motorhole]

Yep, thanks Dan. Fan deffo works on both speeds. I guess coolant in the rad wasn't hot enough to trigger the switch or the switch is faulty. Good to know that I'm capable of following instructions

[E30-Doc]

I was troubleshoot a problem much the same today. for some reason my low temp switch was not switching on properly (I could hear the relay click over but the fan was no good). anyway I have them both set off the high temp relay now and it is working a treat. Mine switches on as soon as it is 1 needle width over the 12 o'clock position with a 80/88C switch and 80C thermostat. Most of the time I live between 1/4 and 1/2, but if I get stuck in traffic for more than a couple mins i creep up towards 1/2. If you ever blow a fuse, or if for some reason your fan doesn't kick in before you get much past the 12 o'clock point. Switch your heater on full blast, this will protect your engine and works pretty well in the short term to keep temps down.

[Motorhole]

Back to this fan jobbie again....

Fan works fine. My concern now is, when warmed up and driving normally with plenty of air flowing through the rad, the temp needle sits just below the 12 o'clock position. However, when idling, the low speed doesn't come on until nearly the 3/4 line. The fan drops the needle just fine, so havn't needed the high speed yet.

But isn't this a bit - you know - tight? Is there a way I can get the fan to kick in earlier - or is this just nothing to worry about?