was stuck in traffic a few days ago and after 45 minutes sitting still in 80 degree weather with my heater on, the temp gauge moved to 1pm, i pulled over and shut off the car, carefully let some water out to relieve pressure from hoses... after 30 minutes was all good, traffic subsided and drove home.
Is not the Aux fan supposed to come on when the temp rises that high?
Anybody have similar situations? fuse? relay? other?
"...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge
The auxiliary fan saves the day when the radiator outlet temperature is 99C - at which point the engine temperature (as shown on the gauge) will be at the 3/4 mark. But, the auxiliary fan is not needed if the rest of the cooling system is operating correctly - and overheating in traffic usually means the viscous-coupled fan has failed or there is debris between the radiators - more info here (for the V8, but the V12 has the same system):
https://www.meeknet.co.uk/e31/BMW_M6...ing_System.htm
P.S. There is no need to reduce the pressure - the expansion-tank cap is a pressure relief valve
Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i
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"...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge
Some years ago my aux fan was not working. Cause: low and high speed relay spades were oxidized, used some contact spray for the relays and the aux fan worked again. Also the plug of the wire which goes into the aux fan at the fan has to be checked, that can also be oxidized.
Shogun tricks and tips for the E32 series are HERE!
http://shark.armchair.mb.ca/~dave/BMW/e31/e31_91.pdf page 0670.0-01 shows you
K21 normal speed
K22 high speed
page 0670.0-00 shows you the relay location chart in front power distribution box.
Print those pages out and leave them in your glovebox, you need it more often. I printed these sheets out and used a marker pen and wrote down in each relay and module what it is. When I open the fuse box cover, I can see it immy
Shogun tricks and tips for the E32 series are HERE!
Check the exact month and year the car was built. You mention 1990, but 1990 could be a 1990 model year or a 1991 model year, here all ETM by built year/month, check again with the correct ETM http://shark.armchair.mb.ca/~dave/BMW/e31/
Shogun tricks and tips for the E32 series are HERE!
There is a resistor (0,47 ohms 100W) mounted on the fan. This resistor have been broken sometimes, check it.
Right from the start of production there were two relays for the auxiliary fan, K21 and K22 - and they were located as shown here:
https://www.meeknet.co.uk/e31/Timms_...lay_Finder.htm
Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i
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"...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge
replaced K21 with new relay... still work go on, granted its on a thermostat...
but wont go on either when switching on the AC...
"...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge
It's not on a thermostat as far as the A/C is concerned - if the compressor runs so should the auxiliary fan......
Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i
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Short the resistor, this will make the fan work at max power. If it starts working the resistor is broken which happens.
tried to short the resistor, nothing... had the AC button on too.
i just read another post where someone wrote that there's a sensor on the passenger side of the radiator... i suppose it gets hot to trigger power to the fan?
short of ripping the entire fan out, not sure what else to do to get this elec fan running...
"...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge
I was chasing the same problem at the weekend - no auxiliary fan and no compressor action. This is normally because the refrigerant pressure is too low and the compressor is inhibited (along with the auxiliary fan). But, I checked the refrigerant pressure and that was fine.
One easy check is to see if the low-speed relay clicks - this is K21:
https://www.meeknet.co.uk/e31/Timms_...lay_Finder.htm
With the ignition in position II, snowflake button in and LED lit, fan speed on automatic (just right of OFF on the rotary control) the auxiliary fan should run. You can now remove K21 and if it is energised you will feel and hear the relay click as you remove and replace it - it is quite obvious.
Have a good look at the relay, it has a diagram on the side of it and you can work out where the pins 30 and 87 are (they are marked underneath the relay) and you can short out the contact sockets and see if the fan runs - it should do.
Don't forget though - if your air conditioning doesn't work then neither will the auxiliary fan run until you are dangerously overheating. If you overheat it isn't anything to do with the auxiliary fan.
P.S. My problems were poor connections at the after-market auxiliary fan connector pair:
....and the compressor didn't run for exactly the same problem....how strange....
Last edited by Timm; 07-23-2018 at 04:11 PM.
Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i
My BMW Repair YouTube Channel
My Current 840ci Sport Individual
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Chase - Heroes to a generation
"...i haven't taken leave of my senses Bob, I've come to them..." -- Ebenezer Scrooge
That's the reason your auxiliary fan isn't running - it doesn't need to as your A/C doesn't work!
Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i
My BMW Repair YouTube Channel
My Current 840ci Sport Individual
My Current 650ci Sport Individual
My E31 Repair and Information Website
My E38 Repair and Information Website
My E63/E64 Repair and Information Website
Chase - Heroes to a generation
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