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I know I'm going to get ragged on for starting a new thread here, but I've done a bunch of searching and have yet to find anything.
I know that the electric fan conversion is a popular mod to do along with the Koyo radiator. I've seen a couple installs, but have yet to find a full write-up on it.
The one issue I've noticed with the installs I have seen is that there's no variable fan speed. It's always 100% on, all the time.
I guess my main question is:
Has anyone done this conversion that can provide some insight? Any hiccups along the way?
Also, is there a way around the aforementioned variable fan speed issue.
You can get a pulsewidth modulated fan controller. You can do something complicated like a series of relays (such as the FD does). However the "simplest" solution is just a single speed fan, controlled by a thermoswitch. The electrical draw can be mitigated by an upgraded alternator. An alternator shop can basically modify your alternator to increase output.
IMO, once you get the fan and the speed controller and all of that, its $$ and complex.
just for tips, the under hood fuse box has a couple of empty 30A spots, and the AAS wiring has switched power, so some of the wiring is done for you.
for a fan the 2001-2004 Mustang has the same size core as the Rx7, and the fan mounts on the side like the Rx7 (most are top and bottom) i haven't tried it yet, but its inexpensive new 3R3Z-8C607-AA or Motorcraft RF-166
for a fan the 2001-2004 Mustang has the same size core as the Rx7, and the fan mounts on the side like the Rx7 (most are top and bottom) i haven't tried it yet, but its inexpensive new 3R3Z-8C607-AA or Motorcraft RF-166
I'm not quite sure what you mean by a variable fan speed, but having a two temp thermoswitch control a two speed fan is a very efficient way to wire the fan up with great temp control and minimal drag on the electrical system. I have a two speed fan + Koyo rad and the fan has never turned on to HI before (granted I've never tracked it since e-fan conversion), so I love that it pulls minimal amps for normal driving.
A few things to note that I did differently than the thread that I shared:
1st gen Nissan Quest fan fits pretty much perfectly once you cut out rad inlet/outlet holes. Heard it fits better than Taurus, but I have not tried myself. Just use whatever is available to you.
Instead of using the huge Audi two temp thermoswitch, use the BMW which is much smaller and can easily be adapted into a generic hose adapter. Low temp is 91 C (196 F) and high temp is 99 C (210 F). Part #: 61311378073
Instead of using the huge Audi two temp thermoswitch, use the BMW which is much smaller and can easily be adapted into a generic hose adapter. Low temp is 91 C (196 F) and high temp is 99 C (210 F). Part #: 61311378073
The BMW 2 stage thermoswith is a nicer solution being a much smaller physical size but the bmw proprietary style connector is the problem...it's hard to find at wreakers ( anything from the 90's into the very early 2000's gets crushed to make room for newer junkers) or super expensive to buy a whole replacement pigtail..I could find individual replacement pins/wires but not the whole connector pigtail outside the bmw dealer...What was your solution for that?
The BMW 2 stage thermoswith is a nicer solution being a much smaller physical size but the bmw proprietary style connector is the problem...it's hard to find at wreakers ( anything from the 90's into the very early 2000's gets crushed to make room for newer junkers) or super expensive to buy a whole replacement pigtail..I could find individual replacement pins/wires but not the whole connector pigtail outside the bmw dealer...What was your solution for that?
So I guess I didn't run into that issue of finding enough old BMWs at the yard. There were two versions of the thermoswitch for different temp settings, but all 90s BMWs had the same style connector. I think I got my pigtail out of an E34, and it's on the rad so it's easy to access. Maybe try a few different yards? There has to be at least one in your area that has a few 90s BMWs. I did look into buying the pigtail new but I agree, way too expensive or hard to find the correct one.
it isnt cheap but they make good products. it can be set up for dual speeds off of one sensor, has a/c bypass, and can be set to stay on after the car is off for cool down if you want.
So I guess I didn't run into that issue of finding enough old BMWs at the yard. There were two versions of the thermoswitch for different temp settings, but all 90s BMWs had the same style connector. I think I got my pigtail out of an E34, and it's on the rad so it's easy to access. Maybe try a few different yards? There has to be at least one in your area that has a few 90s BMWs. I did look into buying the pigtail new but I agree, way too expensive or hard to find the correct one.
Small assist, as the fc scene is still pretty active, and will likely only get more active, as the owners of broken Renesis motors will turn to the older ways ...
Thermoswitch - Part number is Febi Bilstein 61311378073 ~$30
Connector - Part number is BMW-61131378410 ~$7
Gotta say thanks for this thread. Super happy to see there's a reasonable solution for going to a two-speed electric fan on an otherwise stock ecu fc.
Last edited by kabz; 11-26-22 at 09:42 PM.
Reason: Say thanks.
Honestly, I completely forgot I started this thread, but it has resurfaced to me at the perfect time. It's been over a year and I'm finally moving forward with this conversion. Great timing.
In the past year, I've learned a lot more about our cars, and about wiring as a whole, so I think I've got a pretty good solution for this, and some good insights as well. Hopefully this will help anyone else who comes across this thread.
A couple things to note:
-the stock s4 alternator probably will not be up to the task of an e-fan, as it is barely enough to run the car (60-70a IIRC)
-This is the method I chose to use, and may not be the ideal solution for everyone out there. It works for me with the way my car is configured.
So, to continue. I ended up deciding on the Nissan Quest fan as they are readily available, and have 2 speeds. Also, they do fit the FC radiator quite well.
The first hurdle I had to make it over was the connectors on the fan, because apparently Nissan changed the connectors depending on what year of Quest that the fan came out of. Mine appears to be an earlier model, so it has 2 connectors. A 2-pin connector, which is for the high and low speeds, and a 1-pin connector which is ground. In the later fans, Nissan appears to have changed to a single 3-pin connector, which serves the same function as these 2 connectors. See images below for what I mean:
Early 2 pin connector. Top is power, bottom is ground
Later 3 pin connector. Single connector, power and ground
If you end up with one of these older, 2-connector fans, I've done some research and was able to find the connectors. If you have the later 3-pin connector, I haven't looked into that connector, so you can skip this next part, or perhaps someone else can provide some insight.
The larger, 2 pin connector that is used for power, is actually the same style connector that S5 and FD alternators use. This one is easy to find with some quick Googling
The 1-pin connector was a bit trickier. After a few hours of looking, I was able to find a pigtail that would fit. Apparently these connectors are common on Hyundai's, and are typically found connected to the starter-solenoid. However, if you find one of these pigtails online (I only was able to find one on Amazon), I don't believe the wire gauge is sufficient enough (I think 18-20 awg), as the fan will draw around 20 amps. You'll want a pigtail with about 14 awg, which I was unable to find on its own.
So, we'll have to make our own ground connector. Luckily, I've done the legwork and Mouser sells the components individually. The connector is a Yazaki part (PN 7123621440), and is about $1. Super cheap. The terminal and rubber seal used are also made by Yazaki and sold by Mouser, and their PN's are 71162874 and 7157357180 respectively.
Connector Terminal Rubber seal
Now that we've figured out the connectors, we need a way to control the 2 speeds. I ended up going with a Volvo 2 speed fan controller (I forget what cars these came out of, but they're everywhere online. Just search for one). This will save us the hassle of having to wire in 2 relays, and fuse them, and all this other stuff. Simple, cheap, and easy.
Picture of Volvo cooling fan relay I'm referring to
This fan controller has 2 slots on the back of it that I assume were to mount it in the car it came out of. You can mount this wherever/however you wish, but I chose to mount it directly to the fan shroud. I drilled 2 small holes in the shroud, fed zip ties through the slots on the back of the relay, and through the holes I drilled. This keeps it all in one place, and also helps keep the wiring neat.
Lastly, we need a way to tell the fans when to kick on. As was suggested above, you could use a BMW 2 speed thermoswitch, but the proprietary connector is a PITA. I could not find it anywhere, as a pigtail. I could find the connector housing, but could not find the pins/wire seals used. So I opted to go for 2 thermoswitches. Both are made by Setrab, and one is 180F and the other is 190F. These switches(if you don't know how they work) essentially just ground themselves once they hit a certain temp. We just run these switches to the 1 and 2 in on the volvo relay unit, and boom. We have variable speeds.
I forgot to mention which terminal is which on the power side of the Nissan fan. If you're looking into the male end of the connector, the right-side terminal is low speed, and the left is high speed.
Lastly, we just need a place to mount the 2 thermoswitches. This was the hardest part for me to figure out, because there aren't many places that are out of the way. Sure, you could use a coupler on the upper rad house, but that's unsightly IMO.
What I did was use the coolant barb on the rear iron that used to go to the thermowax. I have done the TB mod, and had that nipple capped off, along with the accompanying barb on the back of the stat housing.
I used a 3/8" hose barb to 3/8" NPT adapter, then used a 3/8" NPT to 1/8" NPT step down coupler, then finally used a 1/8"NPT male to 1/8" NPT female splitter, which gives me 2 female ports for the thermoswitches to thread into.
And that's it! That's how I was able to get everything to work, and I am happy with it. If anyone has any insights into other fans/methods, please feel free to add to this thread!!
What I did was use the coolant barb on the rear iron that used to go to the thermowax. I have done the TB mod, and had that nipple capped off, along with the accompanying barb on the back of the stat housing.
Hot damn! That fed the thermowax? I thought it was just a throttle heater or something. I wonder if you just inadvertently helped my identify my 'vacuum leak' that may actually be slow warmup.
--- and now back to your scheduled programming ---
Hot damn! That fed the thermowax? I thought it was just a throttle heater or something. I wonder if you just inadvertently helped my identify my 'vacuum leak' that may actually be slow warmup.
--- and now back to your scheduled programming ---
Yep! There's 2 coolant barbs on the rear iron. The beefy one near the oil filter is for the heater core. The smaller 3/8" one near the intake is for the thermowax.
Well, technically speaking, both that one, and the one behind the water pump housing are for the thermowax.
Essentially coolant comes out from behind the water pump, loops behind the alternator, across the BAC, and into the backside of the thermowax, then comes out and down to that barb on the rear iron.
A bit of a tangent from the cooling fan issue, but some good stuff to know in case anyone wants to tackle the thermoswitch issue a bit differently!
05-05-21, 09:28 AM
