Manual Cooling Fan Switches
 

Installed a set of manual switches to activate the radiator and engine cooling fans. The installation went fairly well but followed the original directions provide online here and although the wiring diagram was correct the photos of the relays were not. I was one relay off which caused the internal AC cooling fan to come on upon immediate insertion of the key and to stay on upon it's removal. A quick check to the Bentley Manual straightened out my problem.

I will eventually follow the Radium King's suggestion to use a 996 Batwing and switches to make this look more OEM but for now I think these will do. Thanks to all that did the original writeups and diagrams!http://986forum.com/forums/uploads02...1558551867.jpg
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That looks great!

Would you mind posting the links to the project? I'm not handy with wiring diagrams, so if you could describe tips and tricks that you employed... I'd be grateful.

Also... links to where you sourced your switches and the relays.

In advance, thanks!

simple, find the correct yellow wire for high speed fans

Use a three prong switch.

1. prong to ground.
2. incoming yellow wire
3. outgoing yellow wire

In switch position 1, the fan operates via computer's instruction based on coolant temp.
In switch position 2, fan is off entirely
In switch position 3, fan is on full time.

pretty straightforward operation.

If I'm not mistaken those relays are already in the car, you only need to make a wire harness to go from the switches you add to manually operate the fan relays .

unless you want to use oem switches. the porsche switches are non-latching so you have to add a latching relay. sad but true.

You are correct. The relays are already present in panel #1. It's simply a matter of attaching the fuse taps to pin 85 on each relay, making the wiring loop and attaching to a switch. Actually pretty easy. Quadcammers suggestion would work but I didn't want to test the wiring as I too am no electrical wizard.

I will post my parts list and suppliers when I get home tonight. The only fiddly work I had to do was to file the opening in the taps a little wider to fit the pins on the relays. If I did it again, I'm not sure I would go to the trouble of wiring up the fans low speed as you will most likely only use the high speed to cool things down quickly. I did it just because it was there.

why did you need these switches?

I installed the switches because I AX the car and it is my daily driver. Both AX and traffic in 90+ degree heat get the temp hotter than I like to see it. Here are the parts I used:

Amazon - 1 Uxcell AC250V/6A 125V/10A 3P SPDT 3 Position Round Button Boat Rocker Switch, 1 Uxcell AC250V/6A 125V/10A 2 Terminal Toggle SPST On/Off 2 Position Round Button Small Boat Rocker Switch.

Fuse Taps from columbineconnectors.com.

To drill the holes I used a progressive drill bit which went up to a 3/4" dia hole. There was a small locator tab on the switch that I clipped off with a pair of snips.

I purchased the wire from Lowes (Southwire 25 ft. two pkgs). I used AMP wire splice connectors and end connectors. Again, purchased from Lowes.

The hardest part of this whole thing was determining where on the batwing to position the switch. As you all know there is not a straight, flat surface on this whole car which is why the switches are positioned higher on the batwing than not. I was concerned that I had to trim off the locking recess on the top of the batwing but it holds fine with no issues. Sorry the relay photo flipped upside down. Still can't figure that one out. Good luck...

thanks for the reply. I'm not sure what AX'ing the car means though to be quite honest. I'm new to Porsches and not being american also doesn't help with some terminology you guys use sometimes :)

thanks

Sorry. AX stands for autocross. It’s where you run a series of time trials around a small course usually set up with cones. In between runs and sitting out in the heat really warm things up. Is this totally necessary, probably not. But others, smarter than me have done it and it’s really simple to do. You can also hide the switches if you don’t want them showing.

Is the system now fully manual or automatic with the ability to turn on as needed

The system operates automatically as designed if the switches are in the off position. By turning the switches on, it allows you to turn on the fans at any time you desire. I did not provide pictures of the engine cooling fan which is the two position switch on the right. But it will allow you to turn on the engine bay cooling fan whenever you desire. It too allows the car to operate automatically when the switch is in the off position. Hope this clarifies.

I've got the two high speed radiator fans wired to a switch and I run it whenever I am on track, it really does help to keep things cool. A side effect is that I have now picked up pending code, something to do with the fans, the car knows that something is up, but it doesn't set a CEL so I don't worry about it. Here's a couple of approaches to possibly resolve this, but since it doesn't set the CEL I don't worry about it.

Manual Override Switches: Engine Cooling Fan and Fuel Filter Heater | Tucks' Travels in a Truck

https://naxja.org/forum/showthread.php?t=1025399

Awesome...love these mods and hacks that do something. Thanks for taking the time to share.
I remember adding heated mirrors to a pickup truck for the winter. Couple hours of effort for YEARS of convenience. I shared my circuits and methods on the forums because that’s what we do.
Kudos


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Thank you TTT but honestly all of the credit goes to the guys before me. I just took what they figured out and tried to follow along as best I could. I won't attempt to name all the smart people on this forum 'cause I'll miss somebody but I think I could practically build the car from scratch (at least I feel that way) with all of the help they provide. Search for manual fan switch and you'll see a lot more info from the guys that really deserve the credit. It's a fun easy mod that really provides some benefit.

OK. So after having installed the replacement fans I'm ready to move on this. I have some questions, and request assistance.

I've read a few threads each illustrating a different, yet like, method of installing a fan switch mod. I choose to go the easiest, simplest, and quickest route. Yeah, right. ;)

Assuming the three prong switch...

One prong I'll connect a wire and attach it to a ground behind/under the console. Correct?

On another prong I'll connect a wire from the two high-speed relay #85 prongs. There will be two wires coming from pins #85... I'll run them into one wire and connect it to a prong. Correct?

That final prong. The "outgoing yellow wire" (#85). To what/where is that wire connected?

It seems like a simple matter... maybe I'm overthinking it (for there are upon these pages more elaborate setups). I just want the fan system to operate as designed... yet affording me the ability to turn on the high-speed fans whenever the occasion calls... and without the car/computer/DME/Etc. knowing there's anythuing going on.

That outgoing wire... any help is appreciated. Thank you! :cheers:

EDIT: And to further understand, if correct. pin 85 is the ground for the top and bottom pin of the relay? When switched, mechanically or automatically, that ground "connects" the top and bottom prong? That outgoing wire from the switch... that's what's stumping me.

Bump #16

mftm

Starter, I'm not familiar with this project and haven't attempted it myself. But from what I understand from reading this thread, Quadcammer and Jgkram are talking about two totally different set-ups. Are you looking to do Quadcammer's set-up or Jgkram's?

Hi Pipe,

Quads.

I just want a manual on/off switch for the high speed fans. I'm no electrician... but can walk around it a bit.

I know one 3 position rocker switch's three prongs will be grounded.

One prong of the rocker switch will be connected by wire to the #85 prongs on the two high speed fan relays.

It's the wire connected to the third rocker switch prong that I'm stuck on... wondering where does that wire go. To what does it connect so that when I hit the switch... the fans come on. Does it go to another prong on the high-speed relays? Quad was unclear about that third wire.

Thanks, Pal.

Easiest way is simple to essentially jump the relay.

Forget my switch.

two prong switch is fine.

Connect one wire to a leg of the high speed fan relay (i forget which leg number it is now).

Connect the other wire to a nearby ground

Done.



for those wanting to do my version, you are putting the switch inline with the yellow wire. so you have wire in from the ecu to one prong, wire out to fans from other prong, and third prong for ground.