My AUX Fan Wiring Idea - need opinions and assistance

[Sean]

Hi Sean.

OK, so as far as wiring, you have the right idea. Using a toggle to trigger the stock high speed relay will work perfect, and cannot backfeed the low speed resistor...if it does, the relay is still open, so there is no circuit to complete.

Your fan on LED is a good idea, but may I suggest 2 things:
1. Use a incandescent bulb. 12 volts is easier than fugging around with LED's.
2. Do 2 bulbs, one for high, one for low.

RadioShack has little housings with or without bulbs, easy install.

Go for it!

Luke

Sweet! Thanks for the tip! I was thinking of doing two seperate bulbs as well. Then I don't have to worry about it being really bright too! AND I could hook it up to the dimmer, if I udnerstand how that works correctly. I'll figure that out - it's not as important.

Thanks again for the tips, Luke! I think this will definately be a go come Tuesday! :)

Question for you Luke, could I run the 12v leads to the lights off of the temp switch. With the low light coming from the low and the high light coming from the high AFTER where my switch is. Would that work too? i just got to thinkin, if I put it after the relays, I may end up with both lights lit if I flip my switch when the low relay is on. May cause confusion.

[nando]

I still don't understand why you guys don't use the stock setup for this - you could even wire it up with an aftermarket fan. the high/low speed relays and temperature sensor are already there!

[Sean]

well i have a smaller engine. I think im going to try to seal the spaces between the rad and condensor, so that the AC will work a little bit better at low speeds

is the stock fan worth anything? becaue im about to chop mine into little peices to get it out

Not really, I gave mine away.

[Sean]

I still don't understand why you guys don't use the stock setup for this - you could even wire it up with an aftermarket fan. the high/low speed relays and temperature sensor are already there!

Yea, I know. But, then there's a condensor in the way, and what's the fun in that anyway? :D lol

[b*saint]

I used my fog lamp circuit and increased the fuse to a 30 amp.

[nando]

Yea, I know. But, then there's a condensor in the way, and what's the fun in that anyway? :D lol

I thought you took your A/C out? like I said, you can easily wire it up to work with an aftermarket fan.

[Sean]

I thought you took your A/C out? like I said, you can easily wire it up to work with an aftermarket fan.

Yep, sure did. Talking generalities though.

And, that's what I'll be doin pretty much. I'll see how it does with the stock temp switch, then I may go nab the other one.

[StereoInstaller1]

could I run the 12v leads to the lights off of the temp switch.

NO!!! The fan switch (thermistor off of the radiator) has very little switching ability, so the extra stress caused by the light bulb would likely be too much stress!

You want to connect it to the same output that runs the fan. You will have to go inside the fusebox.

If you want to connect it to the dimmer circuit as well, here is what you do:

Connect the output of the (low or) high speed relay to pin 85 of a normal SPDT relay. Connect ground to 86, then to 30.

87a will have no connection, but 87 is now a ground when the fan is on (yes, you will need 2 relays) so run that to your lightbulb. Now, run the wire from the dash ligh dimmer to the other wire of the lightbulb...wa-la.

Here is the bitch: you will only have an indicator when your dashlights are on.

So, in other words...kinda dumb, IMHO.

Other than the hassle factor...you could use the relay in a more creative way, making the bulb work in the daylight, using the dashlight dimmer wire as ground part of the time, and dimmed positive the rest of the time, but (HASSLE!!!) I wouldn't bother.

Also, be classy about it...run the wires from the fusebox through the big ass tube running from the bottom of your fuseblock...not out the top!

Luke

[b*saint]

Oh I used my fog light circuit because I took out the fog lights.

[Sean]

NO!!! The fan switch (thermistor off of the radiator) has very little switching ability, so the extra stress caused by the light bulb would likely be too much stress!

You want to connect it to the same output that runs the fan. You will have to go inside the fusebox.

If you want to connect it to the dimmer circuit as well, here is what you do:

Connect the output of the (low or) high speed relay to pin 85 of a normal SPDT relay. Connect ground to 86, then to 30.

87a will have no connection, but 87 is now a ground when the fan is on (yes, you will need 2 relays) so run that to your lightbulb. Now, run the wire from the dash ligh dimmer to the other wire of the lightbulb...wa-la.

Here is the bitch: you will only have an indicator when your dashlights are on.

So, in other words...kinda dumb, IMHO.

Other than the hassle factor...you could use the relay in a more creative way, making the bulb work in the daylight, using the dashlight dimmer wire as ground part of the time, and dimmed positive the rest of the time, but (HASSLE!!!) I wouldn't bother.

Also, be classy about it...run the wires from the fusebox through the big ass tube running from the bottom of your fuseblock...not out the top!

Luke

I was thinking that would be a pain in the ass. I'm gonna PM you a different question relating to the dimmer.

I'll definately try my best to make it clean! :)

Thanks again for the tips, you've been offering good information!

Definately doesn't sound like it's worth connecting to the dimmer. It shouldn't be that bright anyway.

[e304me]

updates?

[nando]

I figured out why my aux fan wasn't working at low speeds.. the BRAND NEW resistor I bought was chipped on one corner when I got it, which kinda pissed me off. but it looked ok otherwise so I put it in.. still no low speed. I messed with it for a while and finally decided to check it's resistance (should be 6 ohms). I got nothing! then I decided to take it out to see if I'm not reading it right, and I realized it's broken into about 8 peices. doh!

[Sean]

Haven't had time to do it. And, I probably won't until I get to school. It's crunch time, and it's a bit more important for me to get stuff packed than it is to wire stuff in my car. lol Bummer, I know. But it works now, I'll mess with it when I know my car won't be moving for a while and I have the time.

[1991 318is]

2 questions.

Can you wire the fan in the same way as the OEM fan in front of the condensor?
i.e. using the ON with A/C and ON with temp switch in the radiator tank.
How would you do this? New fan has two wires and is reversible.

[nando]

Can you wire the fan in the same way as the OEM fan in front of the condensor?
i.e. using the ON with A/C and ON with temp switch in the radiator tank.
How would you do this? New fan has two wires and is reversible.

yeah, easily. you could just connect brown/black & black/black (high and low speeds) to the ground of your new fan, and then the power to the green/black wire. the rest works as normal, although your fan will only really have one speed without the resistor in place.