Vette-kid

I agree, some good ideas dont go old! This is a good write up, ill be saving it for sure. My biggest concern with doing this is figuring out a method to mount it. Im not a great welder/fabricator, so im still a little confused on that part.

Billysvette

Good setup Riggs o'boy ,that is a low cost setup

MotorHead

Nothing worse than sitting in a traffic jam with no place to go and your temperature starts to do the creep, it almost makes you panic. I decided that was never going to happen again especially on an expensive motor.

I have dual 13in. Spal fans with the dual Centrec controller. I have a switch that enables only one or both fans to come on, and I have never really had to flip it to put the other fan on. I have an Autolite pencil lite on my steering column that tells me when the fan is on. I have another red autolite pencil lite on my steering column, one that will come at 220-230 degrees in case I am not paying attention.

I also have a direct line , ( no fuses or relays ) connected by a battery cuttoff switch in my ashtrary to the battery ( where the switch is to select one or two fans ) which is connected to the fan that does not come on automatically in case there is a real emergency, so to sum it up I ain't getting caught watching my motor over heat

PhotoVette1

I run a single Mark VIII Fan, but I have thought about how I would wire a twin fan setup. Basically, it would run both fans in series when not calling for cooling and run both fans in parallel when temperature switch engages. Running fans in series puts both fans in slow speed: they draw 25% power and have 50% of airflow of parallel fans. When temperature switch engages, both fans shift to fast speed. This helps keep underhood temps down, produces a more even air flow over the a/c condensor and minimizes amp spike because fans are shifting from slow to fast, not off to fast.

worship79

I have the focus fans as well. They are connected through a single 6 pin plug. Could someone tell me which wire is what?

worship79

Alright, have the two fans figured out, but shouldn't there be a low and a high speed? Did anybody use the resistor thingy in between the two fans?

worship79

No worries, have that figured out as well

Zero1Niner

Sorry to revive an old thread, but I'm not happy with my current wiring for my focus fans, and wanted to get some feedback.

I'd like for both to be running at a slower speed, then kick into full speed if it starts to get to hot.

Worship79, did you use the focus resistor? How'd you wire yours?

Photovette1, have you wired a dual fan setup as you outlined in the diagram? Or has anyone tried his suggestion?

I'd love some suggestions. I hate the one fan on, then the second when getting to warm.

mrvette

You maybe try wiring the motors in series as a test, and hit with 12 volts, just to see how they run, and if they run pretty well, move some air, maybe put another relay on there, triggered to put them in parallel again when really needed, the default being in series any time the car is running....

worship79

The resistor on mine was bust, so I wired them in sequence: 90C nr. 1 kicks in, 99C the second one comes up too. I kept it pretty simple: a two temps BMW sensor in the intake to trigger the relays.

Zero1Niner

Thanks for the replies guys.

I think photovette's diagram looks interesting...from what I can understand. He hasn't been online since last year, so not likely to reply.

Can anyone give me some thoughts on his suggestion, or walk me through it?

I get the idea, but I think I need a little more help understanding how to apply this method.

Amorget

Basically what it does is as soon as you turn the ignition on it runs the pair of fans in series, thus running them slower. Once the temp sensors grounds it switches over and run the fans in parallel.

Here is how the power runs with temp switch off:


Temp switch on:


Please excuse the MS Paint level tracing

worship79

This is basically how I wired it. You can add complexity by wiring in signal lights and or resistors to add low rpm function. Google "mark iv fan" for more inspiration.

Zero1Niner

Many thanks for the posts and instruction.

Thank you Amorget for spelling that out. On the diagram, what is the function from the IGN side?

Worship79, I will do a little more digging on the mark IV fan setup. Im not looking to make this over complicated, thats for sure. My goal is to have both fans run at a slower speed all the time, then have both at high speed if the temp exceeds ~185, then back to low speed once below 170.

Id like to smooth out the spikes that seem to be imposed having the fans just kicking on an off directly into high speed mode. Seem that will eventually cause headaches, and most likely at a time that I dont want the headache!

The simpler the better.

worship79

I understand and agree; keep it simple! Feeding the fans from the battery or a junction will also help smoothing out spikes.

Amorget

The function from the IGN side is +12 volt only when the key is on. This is what turns the fans on and off with the key.

The diagram as shown will do exactly what you are looking for. To note, I am not aware of any factory vehicle that works this way. All will only turn on the fans when the car gets hot and either a second fan or higher speed when the car gets really hot. However, the primary reason of that would be emissions, imho.

Zero1Niner

Interesting. I'm in California, and overdue for smog once I get it running again. Could that impact my smog inspection?

hereigo

Ditto....I will do this also!

commander_47

Absolutely "fan" tastic!!!! I like this a lot.

It is on the list for my 454 79 project.

commander_47

Absolutely "Fan" tastic!!!!

I like this mod, and have it on the list for my 454.