Official Electric Fan wiring thread!

[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]

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]

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

[e30rapidic]

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

[Mr Mpower]

hi! wich car i need fo find in the junkyard for a fan to my m52 e30? maybe this answer need to be in the first post!

[e30rapidic]

There is a diode underneath the fuse box under the hood. It keeps your a/c compressor from kicking on when your temp switch turns the fan on. It usually doesn't go bad, but if it does, your fan won't run when you click the a/c button.

old bump here...

long story short, snowflake switch doesn't light up and it won't kick the aux fan on. Diode?

Interesting! I'm trying to get my AC working again after may years of not having it. If I press the blue snowflake button, it does not light up. However I took the switch apart and it did light up when I jumped pins 2 and 4. The recirc button lights up and functions as it should.

The aux fan hadn't turned on in years via that switch either so for or the longest time I had the aux fan running through a manual switch since a new thermo switch didn't fix the issue. I rewired everything as it was originally designed and still not getting the aux fan to kick on via the switch. Fan will kick on high and low speeds if I jump it.

I have also disconnected and jumped the pressure switches on the dryer.

***edit - bypassed the the diode and nada. Still no fan or blue illumination***

[ArtClassShank]

It works!

Could have been the fan switch or an air pocket, but high kicks on a tick above middle.

[ArtClassShank]

Just replaced my radiator, and my fan switch. I was having problems where my fan would only kick on with A/C. The fan wires work fine when jumped right before the switch, and the switch is getting plenty hot(confirmed with IR).

My mechanic buddy checked the switch with a multimeter as the car was reaching the warming up milestones, and it wasn't registering any current. He seems to think this is the problem, but I think its air still in the system. He says the only way it could work would be with a 3 prong switch.

I'm not an electrical guy, so hopefully it doesn't come down to wiring, especially since my car was wired by OP.


Forgot to buy connectors today, so I'll have to see if this switch works tomorrow. Hoping I didn't get a bad one.

[dsobering47]

I wired in a new fan, that kicks on only when the fan switch closes for the high side, and I have a manual override switch that grounds the fan relay in case I want the fan on. 80*C thermostat with 80/88 fan switch here.

[RockingM]

My first post would be on a fan thread. You know shit hits the fan...

Anyway. Let see if I got some of this right. I'm going to use the stock ac aux fan for cooling and want it to come on at high. I'll need a new switch for the rad. to fan. I'll need to change the wiring at the fan plug. Is that all to start.
I don't want another fan in the engine bay. I gave up on the clutch fan today because it wanted to cross thread and after it was bounced across the shop a few fan blades flew off so it's in the scrap pile. I'm a logger, that's how I roll. ;)

Now, the wiring at the plug I'm not sure about. I want it to just run on high.

And, any other alternatives for fan switches? I'd like to just pick on up at the auto parts store.

Oh yea, I'm also megasquirting the beast tomorrow.

[nyChris]

If any thread was worthy of being a sticky, this would be it.

Just got my Spal all wired up. Thanks for the info!

[328ijunkie]

:P Glad i could be of some help! Holler if i can help any more.

[Roysneon]

Solid update. I have learned a lot just from reading your posts and derping around with relays and wiring in the past year.

[328ijunkie]

MEGA UPDATE! See first post. Hope that helps most of the people PMing me and stuff. Hard to get back to everyone on an individual basis.

[Roysneon]

Oh God! I finally wired up a relay and put an e36 318i fan switch in the rad. So awesome to have a car that turns the fan on when it's hot and turn it off when it's cooled down. I pulled all the stock wiring from my parts car (late 325is with a/c) and transplanted it to mine (Euro 318t NO OPTION car). The wiring needs to be cleaned up and ran along the stock harness but it works! I'm pretty proud of myself since a few weeks ago I didn't know how a relay worked and a year ago I couldn't read an ETM.