Official Electric Fan wiring thread!

[e30rapidic]

FIXED. Bypassed the AC compressor enable switch behind the lever assembly

[raudonis]

This might help some people that want to add a puller fan utilizing the stock circuit:

I'm building fan wiring following this diagram from 0 (my car doesn't have any from the factory) and something just doesn't add up. Has anyone come up with idea that this diagram is faulty? It shows that pins 30, 85, 86, 87 of relays K1 and K6 are wired in the same fashion, when they actually are not: http://forums.bimmerforums.com/forum...n-and-K1-Relay

K1
30 - hot at all times
85 - hot when ignition on and either snowflake switch on or thermo switch jumped green/black to black
86 - continuous to ground
87 - continuous to fuse 3

K6
30 - hot at all times
85 - continuous to ground
86 - hot when ignition on and thermo switch jumped green/black to black/brown
87 - continuous to fuse 18

[MyE30]

the way the relays are wired is negligible to an extent if you understand how they work because all they are doing is completing a circuit. in your example it doesn't matter if 85 = ground and 86 = power or the other way around. these two terminals are responsible for actuating the rely to complete the circuit; 85 and 86 do not provide power to anything. not sure if that is what you are alluding to or not.

[raudonis]

Theoretically circuit-wise it doesn't matter, but in practice it somewhat does as relay K1 pin 86 is soldered into the PCB from the factory which is hard to access for modification without completely separating the PCB from all the wiring.

[MyE30]

You said you where starting from zero. Why would it matter were k1 and pin 86 go? If on the relay 86 is wired for power, wire 85 to ground. If 86 is ground make sure 85 has power that is controlled by whatever you want to control it.

I believe you are over complicating things.

[wakdog]

I had done this setup and had it running perfectly when I had an M50 in the car 12 months ago, since then I have put in an S50 and new radiator and temp switch. The problem is that now the fan is on as soon as you turn the key and is ignoring the temp switch...

Still need to test the relays, but what parts of the setup in like in the original post would cause my fan to run constantly?

[raudonis]

If none of the fan wiring was altered during the swap - the new temperature switch can be stuck "ON". It should have infinite resistance cold - no continuity for current to pass and switch the fan relay. Might be stuck fan relay. Relay pins 30 and 87 should have no continuity.

[328ijunkie]

Stuck 'closed' relay or switch is where i would look

[pandaboo911]

Got some weird problems here..
I have A/C so I wired both Low/High speed together at the fan connector. (Red + Black together, or Blue/Black + Green/Black before connector)

Using Brown/Black high speed trigger at the fan switch as per directions.

Snowflake button does not turn the fan on.
Grn/Black is grounded when I hook the fan up..
fuse 3 is also grounded when snowflake button is pressed, I think this is why fan the doesn't turn on. wtf?? Is there a short in the fan??

EDIT: Nvm I'm an idiot. AC enable switch wasnt plugged in at the panel. Works great

[bmk]

Has anyone used the a fan from the volvo v70, 850, or 960? Ive read they flow anywhere from 3000-3500 cfm and pull 17 amps on low speed and 35 amps.

JTR suggests that I use the bmw relays to trigger the volvo 2 speed relays, does anyone have input on how this would work?

This will not be in BMW swapped car but rather an LS swapped car if that helps.

Thanks

[328ijunkie]

Simply have the power wires that went to
The stock fan fire the relays built into
The Volvo fan, then run fused power and ground to the fan relay

[E30Pacman]

Thanks 328junkie for this. Got mine working correctly. Question though how do wire it so i can also manually turn on the fan(through snowflake button)? Sometimes the fan switch will let temp get in between half and 3/4ths before it turns fan on. Would like to be able to switch it on before then.

[vpilarrt]

K1 should be activated when you depress the snowflake (assuming you have the middle slider at least halfway open/to the right). Are you running your wiring through K1?

[E30Pacman]

Not best with this wiring stuff. But All I did was follow the directions to wire it for high speed only soo.... Does it make a difference the I previously cut out the aux fan resistor an splice the two black wires together to manually control original aux fan??

[E30Pacman]

man this is driving me nuts. i hit the snowflake button today to activate my orginal aux fan(deleted resistor to run on high long before spal conversion) for no reason, now i keep blowing fuse 18 everytime my spal goes to turn on. i tried moving some wires around to see if theres a short and swapping low and high speed relays, but no luck. anybody help its supposed to be hot this week??