fan controller temperature settings

[Iforgetalot]

I ordered this fan controller, flex-a-lite 33054, for my new electric fan. I have never dealt with anything electric fan and/or controllers. I understand that I have to set the temperature at which the controller will turn on the fan. For my 99 540i what temperature do you guys recommend I set this at? Should I set it up so that it starts the fan right when the thermostat opens or just a few degrees before opening, maybe shortly after? Idk. My car seems to hover between 106-110c, but mostly closer or right at 110c, never more. I am trying and hoping to duplicate the same temperature numbers with the electric fan and in the near future go with a lower temp thermostat, nothing crazy or silly.

[edjack]

Are you replacing the engine-mounted fan with an electric one? If so, where is the sensor to be placed?

Try the same setting: 110 deg C, as measured by the cluster.

[Iforgetalot]

Are you replacing the engine-mounted fan with an electric one? If so, where is the sensor to be placed?

Try the same setting: 110 deg C, as measured by the cluster.

Yes, its being replaced with an electric fan from flex-a-lite, model 398 + aluminum shroud. I started a thread a few days ago on the fan install. Manufacturer recommends placing the push-in temp probe on the intake side of the radiator. Have heard of several people placing the sensor on different locations but for now I think I will place it per their recommendations unless there is a better placement for these cars.

Thank you

[edjack]

The factory sensor for the aux fan is at the rad outlet, at the bottom, but, since this fan is the primary cooling device, it might make sense to place it where they recommend.

BTW, I had an aux fan on my 240Z. Sensor placement was at the top, or engine outlet.

[Iforgetalot]

Cool thanks. I've had several 240/280z since my late teens, fun cars. The latest and greatest had a1983zx t3/t4 turbo swap with MegaSquirt management, fun little cars... My buddy still has two very nice 240z.

[philly98540]

Put sensor on rad outlet side. Fan cools the radiator, so you want the control sensor on the rad outlet. Just like bmw does it. This way at hi way speeds the wind will cool the radiator and the fan will turn off. If you put it on rad inlet side, the coolant will always be hot and the fan will always run even if the return coolant is cold.

[edjack]

Put sensor on rad outlet side. Fan cools the radiator, so you want the control sensor on the rad outlet. Just like bmw does it. This way at hi way speeds the wind will cool the radiator and the fan will turn off. If you put it on rad inlet side, the coolant will always be hot and the fan will always run even if the return coolant is cold.

That depends on where he sets the controller.

[JimLev]

Like edjack said, depends on what temp you set the controller at. It could be mounted in either location.
The lower hose coolany temp would be much lower than the top of the radiator, if you choose this locating just make sure your controller can be set to a low temp.
It would be easier to install it at the top of the radiator.
The non tu engines has the temp sensor in the top pass side of the radiator.
I have my sensor at the top.

[philly98540]

Yeah top is good too on outlet side. I was just saying outlet side of the rad not the hose. Hose is good too, but what I meant was anywhere on outlet side.

- - - Updated - - -

You want the fan to control the returned coolant temp

[JimLev]

After looking at the controller the minimun temp setting is 155-160F, which is probably to high for it to be mounted down at the lower hose (which is where your Aux fan sensor is).
Looks like a nice controller.
https://www.summitracing.com/parts/f...MobileSwitchNo

Your going to need to experiment with the setting to find what works best for your driving style.

[Iforgetalot]

Thanks to all that have responded. I have searched and read until I got tired and there are as many opinions as there are controllers. some say upper, others lower radiator or thermostat housing or the heads, heater core feed line, fins, hoses etc,,,. There is really no "the majority says..." and they all claim their system works just fine, provided the controller and fan work. I am going to try installing it in the upper side of the radiator and see how it goes. I believe all these options will work and it may be a matter of adjusting the settings to driving style like Jim says. The thing is everyone defends their decision and most of them make good sense to me. I may even try a different location and compare results.

[geargrinder]

Huh. Yeah engineering wise rad output makes far and away the most sense. The only argument for rad inlet side I can see is it works 'in advance' aka "ok here's a hot load of water coming in, fire up the fan", but as philly says, the fan could be totally unnecessary if you do that (what if its -10F out? what if you're going 100mph and the fan ain't gonna do squat? etc.), which is why rad outlet side makes way more sense.

I'm guessing their setup is some domestic-car-legacy "thats the way Bubba 'n me alwayz dun it on the old Ferds and Chebbies and so thatz way we gonna keep doin' it!" thing.

Brief searching seems to suggest most people agree the output side is proper engineering.

Jim - 155F is 68C - that's a totally reasonable rad return temp I would think.

For the pre-face cars, the factory Aux fan uses the dual-temp switch based on output side rad temp.... That gives a reasonable 'guideline' to use for temps...
1. initially turns on "low speed" at 91C (196F).
2. goes to high/full speed at 104C (220F)

So if you want the aftermarket to be primary, and to work in advance of the Aux fan coming on, sticking it on the output side of the radiator, and then setting a temp anywhere in the 75-85C (165-185F) range should be fine.

[geargrinder]

There is really no "the majority says..."

Well. The majority of people are forking retards quite often. Whats more important to me is what the experienced/smart/sensible people say. Maybe you did more searching than I did but my quick read on it is the more credible non-bubba sources all seem to suggest output temp measuring, which is exactly what BMW and other premium OEM do. And I'll disagree with you, the outlet temp logic is far more compelling to me than the excuses people have for the inlet side.

I believe all these options will work

But yes - I'm sure it will. The downside of the other way is just that it'll run the fan needlessly.

[geargrinder]

BTW occurs to me why Dumbestic cars may have more likely inlet-temp measuring.

Coolant gauge temp you ABSOLUTELY MUST have either from the block or worst case from the thermostat / output. A temp gauge on the rad output could be catastrophic in case of a water pump failure.

I could see typical Detroit cheapo beancounter engineering where they cheap out and say "well why have 2 temp sensors, we'll just use the one on the t-stat/output side and use that for the gauge and for the electric fan". Then the aftermarket companies copy the dumbestic layout and... there you go, you get electric fans that are just more or less coming on all the time.

[Iforgetalot]

All good points Grinder and Philly98540. So if I understand this correctly, paraphrasing a bit here, by placing it on the outlet side the fan will come on only after the radiator has "lost" it ability to exchange any more heat therefore only coming on to assist/cool the radiator so it can exchange more heat. By reading the outlet temp the system can monitor the ability of the radiator to exchange heat, right? This makes more sense now. Why do people get this so turned around everywhere and why do these manufacturers advice to place it on the inlet side, so bass ackwards. I like my fan not running needlessly, gavel down! output side it is!

[philly98540]

You on a good path my friend! JC, good explaining of the reasons we have bad info all over the place.

[Mach540]

Stick it smack dab in the middle!!!......... Cant argue against that.

[Mannyf540]

Stick it smack dab in the middle!!!......... Cant argue against that.

That's what she said.

[JimLev]

Originally Posted by Mach540
Stick it smack dab in the middle!!!......... Cant argue against that.

That's what she said.

Manny, is that where the sun doesn't shine?

[Iforgetalot]

Finished the install last night. Took me a while working a few minutes whenever I had time. Everyting works fine. The install turned out pretty solid and the fan cycles as its supposed to, well kind of!

I insatlled the temp probe through the fins on the lower outlet side of the radiator. It seems the temp on the lower side is too low to trigger the fan at a reasonable temperarure. Went back on the thread remembering someone said something about the controller low temp not being low enough to trigger the fan if the probe is installed on the lower side of the radiator. Yup, you Mr JimLev Sir, may have hit this nail right on the head. The fan finally came on at 112c and by that time the auxiliary fan was running WOT and falling behind. I turned the car off and the fan continued for about 30 seconds as its supposed to.

After looking at the controller the minimun temp setting is 155-160F, which is probably to high for it to be mounted down at the lower hose (which is where your Aux fan sensor is).
Looks like a nice controller.
https://www.summitracing.com/parts/f...MobileSwitchNo

Your going to need to experiment with the setting to find what works best for your driving style.

Other than that it seems to work just fine. I will move the probe to the inlet/upper side and play with the setting to have the fan come on earlier.

Is it a good idea to set the fan to come on around the same time the auxiliary fan does without the AC on? Seems to me the auxiliary fan is trying to do what the new electric fan will be doing, its just not big or powerful enough to do the job. So it may be a good idea to have the fan operate closely within the parameters of the auxiliary fan. Please advise if wrong.

[JimLev]

Thanks for the update, good to hear you have it working.
I'd set your fan controller to come on a little before the aux fan comes on.