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.

It seems like people are getting a bit confused, perhaps I can help clarify. To manually trigger the fans, all you have to do is ground Pin 85 on the existing fan relays. I used the ground from the phone connector, you literally run a wire from the ground to the relay. You then interrupt this wire with a switch, so you can turn it on and off. With the switch off, the fans work as they always have, with the switch on Pin 85 on the fan relay is grounded and the fan are manually turned on.

You can do this with a simple switch (pictured above), or the OEM switch and a latching relay. The OEM switches do not stay on or off they send a momentary signal when pushed, so you need a relay that stays on or off when it gets the momentary signal from the OEM switch. I chose to only connect the high speed fans, because the low speed fans come on with the AC, so I didn't see the point. And with the OEM switch, you would need two switches one for the high fans and one for the low fans. If you want both the high and low fans with one switch, you use a 3 position switch, the middle/off position is the ground, then the high and low are the other two positions.

You can also wire the engine compartment fan the same way, by grounding Pin 85, but I haven't done it since the relay is in the rear trunk so you need to route the wire a long way.

I have a write-up on the radiator fan mod using OEM switches in the batwing, and how to get them backlight. It's here: http://986forum.com/forums/diy-project-guides/76140-diy-manual-radiator-fan-switch-w-oem-switch.html

Quad's set-up is a little more complicated than JgKram's. This is my understanding of how the existing setup works:

Pin 86 on the relays have constant 12volts. Pin 85 goes to the ECU which grounds it at the appropriate temp, which completes the coil circuit and trips the relay.


Both methos use a Single Pole, Double Throw (3-prong) switch.

Using Quadcammer's method, you'd cut the pin 85 wire (I believe Quad said it was yellow) and, splicing in a jumper wire, run the RELAY side of the wire to the MIDDLE prong of the 3-way switch. Run the ECU side of the wire to the BOTTOM prong, and run the TOP prong to ground. This way, with the switch in the UP position, it completes the circuit with the ECU, and the ECU decides when the fan comes on. In the middle position NOTHING is connected and the fans NEVER come on. (I wouldn't advise that), and in the bottom position the circuit is completed through the ground wire you ran and the fan runs all the time. You can splice the yellow wires from each relay, (left and right side) together and run both to one switch. This would do either high or low speeds. I guess the consensus is to just do the high speed, and don't bother with the low.

Using Jgkram's method, you'd get some fuse taps and connect them to the to the 85 pin of each relay. This keeps existing circuit to the ECU intact. Using jumper wires, splice together the two high speeds and the two low speeds. Run the low speed to the top pin of the switch, the high speed to the bottom pin, and ground to the middle pin. In the up position, the high speed is grounded through the switch, in the bottom position the low speed is grounded and in the middle position the ECU will have control.

You can also use a single pole, single throw (2-prong) switch and run only the high-speed circuits only. Run the jumper wires to one prong and ground the other prong. this way, in the OFF position the ECU would have control and in the ON position you will override the ECU and turn on the fans.

Either setup works fine. It's up to you which one you'd rather use.

Rick... Pipe... thank you for the very clarity I needed. I was overthinking it. I'm no electrical wizard.

Quad... thank you for your help!!

Cheers!

Piper was spot on in his assessment. The hardest part of this modification was crawling in the footwell to hook things up to the relay panel. I must admit that I really wanted to make my modification similar to Rick's as his is more elegant but just wasn't up to it at the time and I took the easy way out. However, I have been very pleased with this modification and have used it often during stop and go traffic in the summer months. I haven't used the engine cooling fan nearly as much so that one could be left off but while your doing the mod, why not.

I ran a wire from pin 85 to ground... and the high-speed fan kicked on (only tested one side).

Just purchased standard round rocker switch... but am thinking that even with the 5 prongs on the back of part #986.613.134.00 (Porsche Boxster Lock Switch Black) I could connect to two of the prongs and achieve the same result, correct? Wire to ground... wire to pin #85... abandon the other three prongs.

Yes? No?

That Porsche Boxster Lock Switch Black would look better than the rocker switch.

Thanks!

Those switches won't work because they're momentary switches. I.e. they don't stay closed when you pull your finger off them. An additional relay needs to be added to get those to work.

Thanks, Pipe. :cheers:

If you want to use those switches then follow Rick's instructions for adding his relay. I think I still have some of the same switches I used and if I can find them you are more than welcome to them. I used a progressive drill bit to drill the holes in the batwing.

Thanks for the offer Jgkram. I appreciate it. I'll pass for now... but will revisit that addition when I get tired of the non-stock rocker switch. That said...

I'm entertaining adding a manual switch to the engine compartment fan. Entertaining meaning is already I've cut and prepared the wires. All I need is to pick up another, matching, switch.... with the exception of running the one, singular, wire from relay to switch. ;)

I'm assuming I'm, via wire and switch, jumping pin #85 of the #8 relay in the frunk... the engine comnpartment fan blower relay. If affirmative... it's the same setup as the radiator fan switch with the exception of one relay vs. two. Now...

That wire running from the #8 relay in the trunk up to behind the center dash console. If anyone has the/ANY method, tips, or tricks to run that wire in the most expeditious manner possible... greatly I would appreciate them.

Jgkram... I like the buttons in the batwing. I removed my wing... examined it... saw the opportunity for some Dremling... and decided against it for the time being. The circuit is so simple that I could remove it in 30 seconds... when I go the wing route. However, I know I will be "entertaining" some cutting in the near future.

I didn't want to mount the switch where it would look terrible out of place. I settled on snuggling it into the side of the cubby (for owner manual) under the steering column. When I asembled the wires and end connecters I heat shrinked everything so you see no silver prongs (even heat shrunk the unused prong). The two wires from the switch I then encased in the round accordian looking sheath hiding thr wires up to under the dash. Looks clean... and doesn't attract "ricer" attention. Until I'm prepared to cut into the batwing the other, engine compartment fan switch, I'll position at the other end of the cubby.

Thanks to everyone who pointed me in the right diorection on this most-easy mod.

Now... about running that wire fron the trunk... past the engine bay... into the cabin... and to behind the center dash console... ;)

Thank you. :cheers:

My car came with an aftermarket backup camera. IIRC, they ran the cable through the hole where the shifter cable goes through. If not that, there's a wiring harness there too. They both go under the center console and into the engine compartment.

Yes this makes perfect sense and I am not sure why one would need more than one relay to ground three pin 85s for all three fans to come at once via a stock momentary contact switch. Three leads through s latching relay to ground. One switch in the empty spot up top controlling it all.

Not sure why one would want low fan speed as well as hi.....it's the same fan no?

I am curious about what the seat heater switch does. Can the two different positions trigger rad fan and engine compartment fan separately .....with two relays of course ( not sure how a step works)

Yes, I never saw the point in hooking up the low speed fans since you can already toggle them on/off by running the AC, and yes it's the same fans, the high or low relays just run them at a different speed.

But you need to be careful with using different OEM switches, they are not all the same internally, so the wiring will be different than how I wrote it up. Most of the OEM switches fall into one of two "types" but there are also some other variations. If you want to use a different switch you need to look at the wiring diagrams in the Bentley manuals to see how the switch is wired internally. I don't think any of the switches with left and right buttons would work with night illumination. The defroster switch I used is basically one button, it doesn't matter if you push the left or right side.. If you don't care about illumination, all the switch has to do is take a 12V input, and send that 12V signal out when you push the switch to trigger the latching relay into the "set" or "reset" position, so you could probably hookup two latching relays with two different functions to one switch.

That's why I went the simple route. One wire from Pin #85 on the relay to a switch... another wire from the switch to ground.

Dunzo.

If there is a reason why people are complicating the setup with relays... looking at wiring diagrams... why would anyone want to do such a simple, simple mod with overkill methods?

Tell me. Thanks! :cheers:

The only reason I can think of is if they want to use original Porsche switches (for appearance). Those switches are momentary switches so a latching relay will be required. If you use a normal style switch no additional relay is needed.

Gotcha. Likely at some point that is the route I'll go. The $10 rocker switches aren't exactly meshing with the interior. However... I've got the setup nicely heat-shrinked... and kind of hidden nestled into that cubby under the steering wheel.

I believed my hookup to be somewhat complicated... and was wrong. I'll overcome the electrical fears and fashion up everything proper.

Then the paddle shifter mod. ;)

Have a great weekend! :cheers:

Radiator high speed fan switch
 

Hi Rick I am new here…so be gentle with me:) I am going to do this mode just checking how this is holding long term? are there any issue since implemented ? I will also be adding a 1N4001 1amp diode to the switch to protect the DME and toggle switch by one way restriction, please let me know.
many thanks for the above write up 👍

Danxx, sorry no one responded. The forum is not what it use to be. As far as the switches go, I have had mine in since the original post. No issues with anything as far as codes or operation is concerned. The only problem you might have is when the switches are turned on they stay on even if you shut the ignition off. It’s possible to drain your battery if you leave them on and forget them.