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Electric Fan Controller using OEM Temp Sensor

51323 Views 97 Replies 26 Participants Last post by  healingartist
After reading bdmonst recent electric fan thread, I was wondering what the thought was on using a fan controller that utilizes the engines OEM temp sensor rather than a temp probe inserted into the radiator. It just seems it would be better to monitor the engine coolant rather than the radiator coolant temperature. I guess in a Jeep I also worry about the temp sesnor being dislodged from the radiator and not providing the proper temp reading to the controller. Does a temp probe inserted into a radiator actually have the proper coupling to efficiently monitor the radiator temperature in a consistent fashion?

Isn't the radiator temp about 20 degrees cooler than the engine, what about if it is raining hard, wouldn't the temperature differential between the engine and radiator now be much higher ?? I would think you would get different readings depending on where in the radiator you inserted the probe??

Here is a link to a fan controller that using the OEM temp sensor for monitoring the engine coolant temperature. As it is a high impedance pick up it does not affect the existing temp gauge or ECM temp input.

http://www.spal-usa.com/fans/automated/tech_sheets/FAN-PWM.pdf

Any thoughts or knowledge/experience here ?

Jim
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I have the Hayden "fin" type probe and controller (It will be actuating a higher amp relay). I don't know where I should put the probe. I have an aftermarket radiator and the fins seem too close together to shove the little Ziptie thing they sent with it through there. I have heard about people just JB welding it to the radiator. That might be a little permanent for me (don't want to have to buy a new radiator if there is a problem. I have also heard about people putting the probe inside the top radiator hose. I kind of like that one but am concerned about it leaking or the probe lead getting damaged. What methods have you guys all used? And how well have they worked? Sorry if this has already been covered....
 

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Hammer - what if your fan doesn't have the two speed resistor pack? I want to rewire mine and would like to do this - but my fans don't have the resistor...Is there an alternative (ballast resistor???) or different wiring scheme that will work for this configuration?

YellowJeep - I put mine on the upper radiator hose (at the rad.) with tie wraps. Then covered it with another piece of rad. hose...again tie wrapped.
 

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Disclaimer: I am a wiring moron.

Okay, I have a Hayden controller (the cheap one that I hear probably won't last too long) that I am going to hook up to my e-fan. The wiring for the controller is crap, all blotchy can't read the words. The wiring diagram for the mod only shows one wire to the controller. The controller has two "leads" on it. So my question is: Is one of them supposed to go to ground? And if so, which one (or does it matter since it is just completing a circuit)? Someone fill me in before I burn up the controller or something hooking it up wrong.
 

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I guess you aren't going to include any of the other devices that are in this diagram and only want to use the Thermostat. I'm not sure which controller you have but - my guess is you need to run fused, switched power to one of the terminals and the other should connect to your fan. The ground will be the other wire on the fan. Again - this is only if you aren't going to use any relays, etc. and just want to use the controller.
 

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Yeah, I am using 2 relays. 1 for high and 1 for low. I also am using the 50A circuit breaker, a switch in the cab, fuse, diode, all that stuff (using a diagram I found on here after looking at all of them). So I am thinking along the lines of what you said I think. Instead of wiring the controller directly to the fan, it is going to a relay for the fan. I guess I am thinking that the relay is grounded THROUGH the controller when the controller closes the circuit (If I ground the other terminal on the controller) which should trip the relay and turn the fan on. Assuming I have the relays and everything before that connected correctly, does that sound right for the controller portion?( I am using the diagram on this thread: http://www.jeepforum.com/forum/f12/electric-fan-install-write-up-taurus-mark-vii-506679/) But I am not using the LED or the high end of the switch (Add high option later if needed, couldn't find 3 pole switch with high enough amp)
 

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OK - I guess I'm a little confused - you aren't using the wiring diagram above?

OK - Just the basics - a switch simply allows a circuit to be completed or prevents a circuit from being completed. The Hayden controller is just a switch - just like any other switch. Instead of a toggle that you flip, it has a probe that causes the switch to open and close. A relay is also just a switch that is controlled by an electrical condition being satisfied. A relay typically allows for a lower amperage circuit (or control) to engage a higher amperage circuit. A relay has a coil that moves the switch inside. For the coil to operate, it needs voltage and a ground. In the above diagram the ground side of that circuit is provided by the controller or the override switch. The voltage is provided by a switched power supply or the override that jumpers around the switched source. So, there isn't a lot of amperage on the switch because all it is doing is operating the coil in the relay. The amperage is pulled through the relay to the fans.

I'm not sure I answered your question - but it would be better to have a little understanding of what is supposed to happen so that you can troubleshoot it if it doesn't.

Clear as mud right?!
 

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That is pretty much what I figured.... I may have a bad relay. I'm not sure, I did get the relay from the junkyard, but I baught a couple just in case. You did answer my question I think. I think you verified what I thaught, being that the temp switch (hayden controller) is just completing the circuit to ground (when temp is met) , then it shouldn't matter which side of the switch is ground...Right??
Oh yeah, I am going to install the probe like you described above. That is the easiest way that I have seen on JF. Thanks
 

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My fan is not starting. I have only had the Wrangler (05) since January, so it has been cool out. I noticed today that it was running a little warmer than normal. Not alot, just a little, so I tried to find a fuse. Then I saw posts about a probe. I don't see a probe or temp switch in the radiator like most have with electric fans. Any help would be great.
Dennis
 

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I'm certainly no expert on the matter, but here's what I did:

I installed a water neck with a threaded npt port on the top, got a brass adapter so the npt temp sensor that came with my fan controller kit would thread into it.

Basically it turns the fan on as soon as the T-stat opens and starts circulating, I average about 5-10 minutes of fan on/off cycle unless I'm running it hard.

As it sits now, the T-Stat opens, fan comes on, cools the water/engine, T-stat closes, fan shuts off. I have the temp control on the fan set to ~170 degrees so I know if the Tstat is open the fan is running .

It all works well, cycles on and off and keeps my engine cool.
 

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On the 2nd incarnation of radiator and e fan I re used the FAL 13" with the zip tie mounts and the fin insert sender probe, after about a year or so the zip ties and probe ever so slightly abraded the cooling tubes of the radiator creating seeping weep of coolant. Lucikly I was turned onto a free new in box 3 row radiator from another Jeeper that reconsidered the Corvette motor transplant. I got another controller with a thread in type of probe and found from Summit (IF I remember correctly) a short internal sleeve that fit into the upper radiator hose with a bung for this probe incoporated into it.
Since this time I've recently purchased an '89 (marked) Merc Mystique double fan.

JeepHammer, I really liked your post about keeping things civil in this thread, a rule that too many these days seem to falter on. I'm intending on using your clear, concise wiring diagram on 'Black Betty' but if this is the resistor;







could you clue me in on how I would alter the wiring from your diagram? Thanks and a lift of the lynch lid!
 

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Went back to the boneyard looking for a bank of relay sockets (small footprint) and I found two more 70/80 amp relays for free with a more contemporary number;





I scanned several vehicles for small footprint relay pods, but so far those that take Bosch style relays are 6x9" and larger.
 

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Help Please for a non-gear head

Hi Guys - I figure most of you are guys…anyway. My husband died and left me with an 84 cj7 which I've been fixing up to sell to pay his medical bills (rebuilt engine, howell, tdi, etc...its a new car in an old fixed up body) I've done just about everything to it but now I'm stuck with the electric fan/thermostat debacle, and my head is swimming. I've had a friend do most of my work for me (very well) but he left scratching his head when no matter what temp and fuel gauge we put in, they wouldn't work. I just took the jeep over to a recommended mechanic who is trying to figure out how to hook all this stuff up since the temp sensor is hooked up to the fan so what do we do with the gauge?
Can someone please explain to me how we can hook the fan up to the sensor/controller and the gauge so I can get this sweet baby into the loving hands of a jeep enthusiast? I want the car to be in the best shape for the next person who will love it as much as my guy did.:kiss:
 

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Hi Guys - I figure most of you are guys…anyway. My husband died and left me with an 84 cj7 which I've been fixing up to sell to pay his medical bills (rebuilt engine, howell, tdi, etc...its a new car in an old fixed up body) I've done just about everything to it but now I'm stuck with the electric fan/thermostat debacle, and my head is swimming. I've had a friend do most of my work for me (very well) but he left scratching his head when no matter what temp and fuel gauge we put in, they wouldn't work. I just took the jeep over to a recommended mechanic who is trying to figure out how to hook all this stuff up since the temp sensor is hooked up to the fan so what do we do with the gauge?
Can someone please explain to me how we can hook the fan up to the sensor/controller and the gauge so I can get this sweet baby into the loving hands of a jeep enthusiast? I want the car to be in the best shape for the next person who will love it as much as my guy did.:kiss:
Can you take some pictures?
 

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Thanks to all for your help. I've found a wiring genius who is well versed in the fan, gauges situation and it appears that besides the fuel sensor being bad and now on the mend…so is my man's beloved jeep… I'll let y'all know when its up for sale.
 
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