DIY: Flex-a-lite Variable Fan Speed Controller
07-30-2007, 07:58 PM
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2005 Ti Gray RX-8 - SOLD
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DIY: Flex-a-lite Variable Fan Speed Controller
Here is another DIY I am doing since I didn't see any others in the sticky listings....
This fan controller is really neat, really simple, quite flexible, and maybe a cheaper alternative to the other options out there that take away control of the 2 fans from the ECU. Here in AZ it is nice to keep the bonnet temps a little cooler, and also lessen the chance of the fans staying on full blast for 5 minutes after the car is shut off (I think this one is like 30 sec. max, and will come on by itself after shutdown depending on temp).
It is also nice to have the manual control to kick the fans on when you know you are going to be naughty on the mountain run etc...
BEFORE YOU GO ANY FURTHER, MAKE SURE YOUR BATTERY IS COMPLETELY DISCONNECTED AND AWAY FROM THE CAR - THESE FANS CAN SLICE FINGERS LIKE A CUISINART CHOPS CARROTS.
This is not a system by where you can leave the ECU in the circuit.... is this installation, you will be cutting the fans out of the equation, but leaving all the 3 relays hooked to the ECU. As some of you know, the ECU controls its cooling needs by running a set of 3 relays to determine which fan, parallel or series wiring etc...
In my DIY, you will be running both the Hi and Low fans at the same time in parallel. These fans in series barely make a breeze, but in parallel they make a hurricane. Don't worry though, the Flex-a-lite starts things off at 60% throttle and slowly bumps things up as needed, so you aren't going to hear the tornado under the hood every time the fans come on. Also, this controller has soft on and soft off, so it will always ramp up or down the speeds, so no major voltage sags/spikes etc...
This unit also has input controls for manual over-ride ON and manual over-ride OFF. I don't plan on doing any water crossings, so I have only wired in a manual switch for full manual ON.
This unit also has an 'A/C compressor on' input, and will work with both the negative and positive style triggers to kick the fans on when the A/C clutch is engaged.
I know there are only two wires to the clutch unit, and if somebody knows which style the RX-8 has, I will tap into the wire, hook it up and test for you all. Otherwise,
I don't use my A/C, so I didn't plan on tapping into this circuit.
The nicest thing about this controller (and the reason we all get fan mods to begin with) is to kick the fans on at an earlier point as to 'get ahead' of the engine heating
before it gets us out of optimal operating temp range...where it is easy to maintain, but harder to lower temps once they are there. It has an adjustable pot to control when the fans come on, and when my CarPC is back up and running, I will use sCANalyzer to look at coolant temps and adjust the fans to come on (60% power remember) at 185 Deg F. Right now it may already be there, as it is definitely coming on sooner than stock, but I'd like to know more precisely since I have the OBDII connection etc...
This system uses a two wire thermocouple or thermistor to feed temp info to the box. It is simply a matter of stuffing a metal probe through your radiator fins nearest the inlet of the radiator. So simple in fact, that you will see in the pics, that it only took me three holes to accomplish a good spot
Scary stuff though, pushing an object (on purpose) right through the fins!
This is a relatively easy install, but it did take me about 5 hours, even though the front of my car is already apart (putting on MS bumper this weekend too!)
If I did it again, I could certainly do it in a couple hours.... I don't like rushing, and I enjoy working on my car. If you want simple and fast, get the Mazsport mod, or your ECU RB re-flash. Also, unless you can get yourself some factory fan wire connectors, you will be hacking into your factory harness. Never bothers me, but some folks
simply will not hack and slash OEM stuff. I understand. Most of the time was me figuring out how and where I was going to mount things, run wires, and I also decided to rip out the top part of the battery box, and the little air intake tube for the battery box (what a PAIN!). Since I had the intake and battery box out, I also experimented with other battery orientation, but the stock air box is just too big to do anything but normal arrangement at this time. Please excuse the messy engine bay and pathetic battery connections!
First, gut the front end of your car....well this pic is just for fun...all you need to do is remove the airbox and battery/tray. Of course if you know where to get the direct fan wires elsewhere, you can avoid some of the disassembly here....my car was already apart for other stuff so I hacked in right at the fans. Plus you need to get access to the temp probe from the fan shroud side (battery side) anyways.
Here is the actual controller:
Here is where I decided to mount mine:
The temp probe, stuck through the front of the radiator (try number 3)... the first attempts hit the inside of the fan shroud to soon, you want 1/2 - 3/4 inch of the pointy part of the probe to be sticking out on the other side. This spot just happend to do just that when it hit the shroud.
This is the fan side of the radiator, as you can see, I have already placed the black rubber cap on the probe so that it does not fall back out the front... in this case it was a neat trick to get the cap on, as the shroud is in the way.
Overview after hacking out the fan connectors and taping up the main loom
The hacked out fan connectors, now soldered to the new black and red leads in parallel.
Separate the + and - and tape em up
I yanked the wire loom mounting tab, and folded it away. In its place, I mounted the big fan's connector assembly to give me a little more slack in the lines.
Overview of the fans and their new wire leads.
The controller mounted in it's spot, with all the wires hooked up and zip tied.
Some connectors are not being used by me, since I do not have the A/C clutch signal hooked up, or a manual over-ride 'off' switch installed.
You will need to run a line from the 12V ACC + to the controller, so that when the key is on, it arms the controller. It has a built in delay (I think 5 sec) to
prevent the fans from coming on while starting the car, in the rare case the temp is above the threshold before starting the engine.
As far as optional components go, I installed a simple automotive switch under the dash, which will turn on the fans full blast whenever I want.
It is one wire from the controller, switched to ground to activate. As mentioned earlier, you can also hook up another switch to ground, to force the fans
off when crossing water etc. Another important one for most people is to hook in the lines to the A/C compressor clutch. We need to figure out if the
RX-8 trigger is negative or positive for the clutch, and then hook up the appropriate wires. The controller can accept both kinds of signals, but only one type can be
hooked up at a time.
Testing the system is as simple as turning the key to 'ON', waiting a few seconds, and hitting the manual over-ride switch (if you've installed it). If your fans come on and are both blowing upwards, you are done except for setting your temp threshold. Basically, you will need to know your engine temp (say, via OBDII) and turn the blue control pot until the fans come on while the desired turn-on temp is being displayed. My goal is to have them come on (60% remember) at 185 Deg F. BTW, there are 3 red status LEDs on the controller to let you know it has got ACC power, and also one each for manual ON/OFF
state.
Here are the details of the product as sold by Summit Racing. I got mine from rskolstoni as he never installed it (thanks!).
http://store.summitracing.com/partde...5&autoview=sku
P.s. Thanks to StealthTL for added info during my install
Final notes- after running it for a week now, everything is great. The fans are on almost every time I pull into my driveway now, but only stay on for a few seconds after the key is pulled. Sometimes they will actually come back on again for a few seconds, but that has only happened a couple times. Keep in mind our ambient temps are still 90-100 deg F here in AZ, and I drive pretty spirited everywhere I go. I can't wait to get my CarPC up and running again so I can monitor things better. I am working on that this weekend.
This fan controller is really neat, really simple, quite flexible, and maybe a cheaper alternative to the other options out there that take away control of the 2 fans from the ECU. Here in AZ it is nice to keep the bonnet temps a little cooler, and also lessen the chance of the fans staying on full blast for 5 minutes after the car is shut off (I think this one is like 30 sec. max, and will come on by itself after shutdown depending on temp).
It is also nice to have the manual control to kick the fans on when you know you are going to be naughty on the mountain run etc...
BEFORE YOU GO ANY FURTHER, MAKE SURE YOUR BATTERY IS COMPLETELY DISCONNECTED AND AWAY FROM THE CAR - THESE FANS CAN SLICE FINGERS LIKE A CUISINART CHOPS CARROTS.
This is not a system by where you can leave the ECU in the circuit.... is this installation, you will be cutting the fans out of the equation, but leaving all the 3 relays hooked to the ECU. As some of you know, the ECU controls its cooling needs by running a set of 3 relays to determine which fan, parallel or series wiring etc...
In my DIY, you will be running both the Hi and Low fans at the same time in parallel. These fans in series barely make a breeze, but in parallel they make a hurricane. Don't worry though, the Flex-a-lite starts things off at 60% throttle and slowly bumps things up as needed, so you aren't going to hear the tornado under the hood every time the fans come on. Also, this controller has soft on and soft off, so it will always ramp up or down the speeds, so no major voltage sags/spikes etc...
This unit also has input controls for manual over-ride ON and manual over-ride OFF. I don't plan on doing any water crossings, so I have only wired in a manual switch for full manual ON.
This unit also has an 'A/C compressor on' input, and will work with both the negative and positive style triggers to kick the fans on when the A/C clutch is engaged.
I know there are only two wires to the clutch unit, and if somebody knows which style the RX-8 has, I will tap into the wire, hook it up and test for you all. Otherwise,
I don't use my A/C, so I didn't plan on tapping into this circuit.
The nicest thing about this controller (and the reason we all get fan mods to begin with) is to kick the fans on at an earlier point as to 'get ahead' of the engine heating
before it gets us out of optimal operating temp range...where it is easy to maintain, but harder to lower temps once they are there. It has an adjustable pot to control when the fans come on, and when my CarPC is back up and running, I will use sCANalyzer to look at coolant temps and adjust the fans to come on (60% power remember) at 185 Deg F. Right now it may already be there, as it is definitely coming on sooner than stock, but I'd like to know more precisely since I have the OBDII connection etc...
This system uses a two wire thermocouple or thermistor to feed temp info to the box. It is simply a matter of stuffing a metal probe through your radiator fins nearest the inlet of the radiator. So simple in fact, that you will see in the pics, that it only took me three holes to accomplish a good spot
Scary stuff though, pushing an object (on purpose) right through the fins!This is a relatively easy install, but it did take me about 5 hours, even though the front of my car is already apart (putting on MS bumper this weekend too!)
If I did it again, I could certainly do it in a couple hours.... I don't like rushing, and I enjoy working on my car. If you want simple and fast, get the Mazsport mod, or your ECU RB re-flash. Also, unless you can get yourself some factory fan wire connectors, you will be hacking into your factory harness. Never bothers me, but some folks
simply will not hack and slash OEM stuff. I understand. Most of the time was me figuring out how and where I was going to mount things, run wires, and I also decided to rip out the top part of the battery box, and the little air intake tube for the battery box (what a PAIN!). Since I had the intake and battery box out, I also experimented with other battery orientation, but the stock air box is just too big to do anything but normal arrangement at this time. Please excuse the messy engine bay and pathetic battery connections!
First, gut the front end of your car....well this pic is just for fun...all you need to do is remove the airbox and battery/tray. Of course if you know where to get the direct fan wires elsewhere, you can avoid some of the disassembly here....my car was already apart for other stuff so I hacked in right at the fans. Plus you need to get access to the temp probe from the fan shroud side (battery side) anyways.
Here is the actual controller:
Here is where I decided to mount mine:
The temp probe, stuck through the front of the radiator (try number 3)... the first attempts hit the inside of the fan shroud to soon, you want 1/2 - 3/4 inch of the pointy part of the probe to be sticking out on the other side. This spot just happend to do just that when it hit the shroud.
This is the fan side of the radiator, as you can see, I have already placed the black rubber cap on the probe so that it does not fall back out the front... in this case it was a neat trick to get the cap on, as the shroud is in the way.
Overview after hacking out the fan connectors and taping up the main loom
The hacked out fan connectors, now soldered to the new black and red leads in parallel.
Separate the + and - and tape em up
I yanked the wire loom mounting tab, and folded it away. In its place, I mounted the big fan's connector assembly to give me a little more slack in the lines.
Overview of the fans and their new wire leads.
The controller mounted in it's spot, with all the wires hooked up and zip tied.
Some connectors are not being used by me, since I do not have the A/C clutch signal hooked up, or a manual over-ride 'off' switch installed.
You will need to run a line from the 12V ACC + to the controller, so that when the key is on, it arms the controller. It has a built in delay (I think 5 sec) to
prevent the fans from coming on while starting the car, in the rare case the temp is above the threshold before starting the engine.
As far as optional components go, I installed a simple automotive switch under the dash, which will turn on the fans full blast whenever I want.
It is one wire from the controller, switched to ground to activate. As mentioned earlier, you can also hook up another switch to ground, to force the fans
off when crossing water etc. Another important one for most people is to hook in the lines to the A/C compressor clutch. We need to figure out if the
RX-8 trigger is negative or positive for the clutch, and then hook up the appropriate wires. The controller can accept both kinds of signals, but only one type can be
hooked up at a time.
Testing the system is as simple as turning the key to 'ON', waiting a few seconds, and hitting the manual over-ride switch (if you've installed it). If your fans come on and are both blowing upwards, you are done except for setting your temp threshold. Basically, you will need to know your engine temp (say, via OBDII) and turn the blue control pot until the fans come on while the desired turn-on temp is being displayed. My goal is to have them come on (60% remember) at 185 Deg F. BTW, there are 3 red status LEDs on the controller to let you know it has got ACC power, and also one each for manual ON/OFF
state.
Here are the details of the product as sold by Summit Racing. I got mine from rskolstoni as he never installed it (thanks!).
http://store.summitracing.com/partde...5&autoview=sku
P.s. Thanks to StealthTL for added info during my install
Final notes- after running it for a week now, everything is great. The fans are on almost every time I pull into my driveway now, but only stay on for a few seconds after the key is pulled. Sometimes they will actually come back on again for a few seconds, but that has only happened a couple times. Keep in mind our ambient temps are still 90-100 deg F here in AZ, and I drive pretty spirited everywhere I go. I can't wait to get my CarPC up and running again so I can monitor things better. I am working on that this weekend.
Last edited by Chamberlin; 08-05-2007 at 03:00 AM. Reason: add more content
08-02-2007, 01:57 PM
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Thanks!
p.s. anyone know how to get hosted photos to show up in the body instead of being links? I am using the IMG tag, but it is not working like usual.... it'd be nice not to have to click links to see the pics.
p.s. anyone know how to get hosted photos to show up in the body instead of being links? I am using the IMG tag, but it is not working like usual.... it'd be nice not to have to click links to see the pics.
08-08-2007, 11:57 PM
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Thanks man! My heater is constantly putting out heat too, but I don't necessarily want it too... I know I have the heater control panel problem too, but I never truly feel outside air temps in my car even when it appears to be set properly to cold... Please somebody make a DIY for completely bypassing the heater core (maybe with a ball valve) or something!!! I want straight outside air temps dammit!!!
08-09-2007, 09:01 AM
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Oh, my AC/heater doesn't have a control panel problem. I got desparate and ran the heater on purpose to act as an auxilury radiator for the car. 
It works. You get very hot, but the engine doesn't puke and you can take a shower when you get home.
It works. You get very hot, but the engine doesn't puke and you can take a shower when you get home.
Last edited by musclecarconvrt; 08-09-2007 at 09:05 AM.
08-09-2007, 11:44 AM
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Oh sorry man, I knew what you meant about using the heater for engine cooling, I do it sometimes myself; I just worded my post poorly... That damn heater will burn you won't it! I am surprised it hasn't melted my vents yet!
08-13-2007, 01:03 AM
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Finally got my CarPC back up and running tonight, all it took was ditching a platter style hard drive and replacing it with a solid state IDE drive!!! (at $25 a GB!!!)
But anyways, I have been driving around tonight and watching the temps, looks like wherever the pot was set from the factory, the fans start to come on around 195-200. Driving hard, with the fans on manual override on, and outside night-time temps of 94 deg., I was able to keep the temps at 195 or less, and then when going back down to normal driving, the temps just kept falling all the way down to 179.6!!! Then I pulled into my neighborhood and the temps went up slightly to 181 or so, since the speeds were so slow. Remember I am referencing the OBDII coolant temp on sCANalyzer, I have no idea what the true Flexalite probe temp is, but it is mounted close to the inlet of the radiator, and I will base my adjustments off of OBDII regardless (what else can I base them off of!!!). I am shooting to make the fans come on at about 185 deg. Should be easy as pie with the software now.
Just to clarify, I have a Seibon vented hood, and I am running about 15-20% coolant to 80-85% distilled water, with redline water wetter additive. Very happy now, just hope the Yellow top battery/charging system can hold out with all the peripherals running and the fans being used more..but so far so good! Hell that new IDE solid state drive uses a whole Watt less power than a normal desktop hard drive!
cheers,
-C
But anyways, I have been driving around tonight and watching the temps, looks like wherever the pot was set from the factory, the fans start to come on around 195-200. Driving hard, with the fans on manual override on, and outside night-time temps of 94 deg., I was able to keep the temps at 195 or less, and then when going back down to normal driving, the temps just kept falling all the way down to 179.6!!! Then I pulled into my neighborhood and the temps went up slightly to 181 or so, since the speeds were so slow. Remember I am referencing the OBDII coolant temp on sCANalyzer, I have no idea what the true Flexalite probe temp is, but it is mounted close to the inlet of the radiator, and I will base my adjustments off of OBDII regardless (what else can I base them off of!!!). I am shooting to make the fans come on at about 185 deg. Should be easy as pie with the software now.
Just to clarify, I have a Seibon vented hood, and I am running about 15-20% coolant to 80-85% distilled water, with redline water wetter additive. Very happy now, just hope the Yellow top battery/charging system can hold out with all the peripherals running and the fans being used more..but so far so good! Hell that new IDE solid state drive uses a whole Watt less power than a normal desktop hard drive!
cheers,
-C
08-15-2007, 12:41 AM
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Final report/update: Today when I got home, I left the car running, and using a mini flat-head screwdriver to adjust the 'turn on pot', it only took me three cycles of experimenting to get the fans to turn on at EXACTLY 185 deg registered on the OBDII temp gauge. The neat thing is, is that the fan speed reacts progressively as you turn it, as well as the fan-on LED light bulb. SO when you hit your coolant temp target, just turn the screw until the fans barely come on, and you are done, save for a couple of heat-up/cool-down test cycles for fine tuning. I might even run a LED circuit into the cockpit so I can see the intensity of the LED, and how much the fans are on... anyways, THAT IS ALL!
-C
-C
08-15-2007, 09:53 PM
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Thanks again for the follow up. This DIY is in my future. It's been right at 100 degrees or more for two weeks now here in TN. Today when I left work it was 104. 20 minutes down the road it hit 107! That may be easy in AZ, but that's just plain HOT here in TN.
02-23-2009, 09:20 PM
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Another follow up:
I did end up running a LED to the cockpit, paralleled with the fan circuit (with a current limiting resistor of course) and it is a great visual indicator to see that your fans are on or not... Since the blue LED is connected with the fans, it gets brighter as fan speed increases...pretty neat...
The ONLY problem I have had with this set up, is that somehow, or somebody cut my temperature sensor lead wires (maybe it got pinched in the hood, or HID tilting mech, I have NO f$#^@ing idea, it was a crazy clean cut, like somebody with a pair of dykes did it) and my car overheated in traffic since the fans never came on... that was scary.... white steam pouring out of the hood, I thought I had a engine bay fire. Pulled over, figured it out, topped off the radiator with distilled water, and limped it home with the fan's over-ride switch flipped on (to be on the safe side) all while monitoring temps on the sCANalyzer....
SO, be sure to run your wires safely and smartly.
-C
I did end up running a LED to the cockpit, paralleled with the fan circuit (with a current limiting resistor of course) and it is a great visual indicator to see that your fans are on or not... Since the blue LED is connected with the fans, it gets brighter as fan speed increases...pretty neat...
The ONLY problem I have had with this set up, is that somehow, or somebody cut my temperature sensor lead wires (maybe it got pinched in the hood, or HID tilting mech, I have NO f$#^@ing idea, it was a crazy clean cut, like somebody with a pair of dykes did it) and my car overheated in traffic since the fans never came on... that was scary.... white steam pouring out of the hood, I thought I had a engine bay fire. Pulled over, figured it out, topped off the radiator with distilled water, and limped it home with the fan's over-ride switch flipped on (to be on the safe side) all while monitoring temps on the sCANalyzer....
SO, be sure to run your wires safely and smartly.
-C
02-10-2020, 07:41 PM
#14
sorry, big bump...
I got a Flex a Lite 420, and I am going to be using the variable speed controller. I do use my AC a lot in the summer, so I need to know how to wire up the compressor to the controller. The instructions that Flex a Lite has for this are not very clear. Anyone have any insight?
I got a Flex a Lite 420, and I am going to be using the variable speed controller. I do use my AC a lot in the summer, so I need to know how to wire up the compressor to the controller. The instructions that Flex a Lite has for this are not very clear. Anyone have any insight?
02-10-2020, 09:45 PM
#15
Well you should ask and search before lighting your wallet on fire while it’s still in your pocket
you don’t really need a controller imo. If you can send it back and be reimbursed that may be your best option. Then just cut off the OE fan connectors and wire these fans directly in place of the OE fans. The factory ECU will control all of that as programmed.
you don’t really need a controller imo. If you can send it back and be reimbursed that may be your best option. Then just cut off the OE fan connectors and wire these fans directly in place of the OE fans. The factory ECU will control all of that as programmed.
02-11-2020, 07:00 AM
#16
no, I ask because they threw it in the box with the fan. Originally, I was not planning on using it, but because the quality seems decent, and the fact that a free solution to reduce my fan trigger temps was included with my new shroud, why not use it? Also, it allows me to have a manual on (and off if I want) without having to shove wires under relays in the fusebox
Last edited by AMDguy; 02-11-2020 at 07:01 AM. Reason: more stuff
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