radiator fan question.........
 

today i took of the clutch fan and shroud so that i could put on an electric fan. i picked up an electric fan at the junkyard and put it on.

my question is: how do i wire up the electrical fan so that it comes on when the engine reaches normal temp?

there are 2 wires (blue=power, black=ground)

my friend did it somehow but i dont remember what he did to make it work like i want to.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/how-control-electric-fan-factory-thermoswitch-886862/

long thread with lots of different diagrams, but basically the easiest thing to do is locate a thermoswitch that will trigger a fan relay when the temperature gets high enough. The s5 style switches are easier to hook up.

where is a thermoswitch on the s5 non turbo at? is there one on the back of the thermostat housing? and since i have two wires on the fan, cant i just ground the black wire of the fan and attach the other wire to the thermoswitch?

Oh God, NO!
The unit on the back of the pump housing is not a switch, it's a sensor...completely different animal, leave it alone.
There is an unused pad on the pump housing that can be drilled/tapped to accept a switch or you add an adaptor to the upper rad hose or even maybe directly into the rad itself.
Where ever you end up locating the switch, it will control the relay that feeds the fan, not the fan itself.

ok, so i ended up buying a relay kit for the fan. it came with a thermostat switch and all necessary wiring and the diagram to wire it up

i hooked everything up exact to the diagram, and the fan does not come on. the relay is as follows:

black wire- ground
orange wire- + wire from fan, - from fan to ground
red wire- + battery terminal
brown wire- prong 1 of thermo switch
yellow wire- prong 2 of thermo switch, then other end goes to switched ignition source
blue wire- secondary fan(which is not being used)
green wire- a/c compressor( which is not being used)

i wired it all up according to the above wiring like it says, and the fan does not come on when reaching full temp. the only way i can get the fan to turn on is by taking the green wire that isnt being attached to the a/c compressor (which is not on the car) and touching it to the + side of the battery. it will turn on when cold, warm, hot, etc. i dont know what the problem is. somebody have a suggestion for me? thanks!

Can you post the directions you're working from?
What you describe sounds weird as hell.

yeah, ill get it on here shortly.......

http://www.glowfoto.com/static_image.../img6/glowfoto

this is the schematic that i was using. i wired it up exact to this.

i also used aaroncake.net and still no go...

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OK.
You should be able to jumper the yellow from the ignition to the brown on the relay- effectively bypassing the thermoswitch- and activate the fan.
If it works, all your wiring is correct and the switch is the problem.

ok. but i just bought this brand new. should i get the stock switch that goes into the bottom of the radiator specifically for the rx7?

ok i see what you are saying. i already did that and the fan did come on. where can i find the switch locally? autozone has none, i already checked on it.

is there a switch identical to the one i need that may fit another vehicle i could get?

NAPA has billions of thermoswitches.
All you need to know is the thread size and the temp you want.

Sounds like a lot of effort to get that fan. I think my friend, he was using a switch to activate the fan and had the fan running on all times when he was driving.

He had to turn off the switch when the car is off or else his battery drains.

That's how he handled his rx7 when he added an electrical fan.

cool, thanks for the advice.

The switch that goes in the bottom of the radiator is not for a fan. It switches around 65F, and is used by the ECU for a completely different purpose. This is also not a very good place for a thermo-switch for a couple reasons: 1) it won't actually be in the coolant, and 2) it's on the colder side of the radiator. I tried this location with a 195F switch, and the fan did not come on until about 210F.

Your friend did it wrong.
IMO, the entire point of swapping to an efan is to exploit the control it offers.
If you're just going to run it all the time, the efan is no better- and more complex- than the stock thermoclutch setup.

Manual control of the fan means constantly monitoring the temp and trying to anticipate situations that may require extra cooling (like sitting through a few left turn light cycles)...attention better spent on actually driving instead of nursing the cooling system.

well then, does the coolant temp switch even have 2 prongs? and where exactly is it located then?

https://www.rx7club.com/2nd-gen-archive-72/diy-electric-fan-shroud-808292/

There's a wiring schematic for it here as well. I went down to autozone and grabbed a fan relay kit for it, but that was a bad idea. Turns out that you can start a small fire with the A/C diode. It's supposed to prevent the compressor from coming on every time the fan starts, but mine burned right up after a few cycles of the fan.

I mounted the fan switch on the thermostat housing. Just drill a little hole and tap it then screw the switch in. Some switches have a single lead, which will ground when the temp is high enough. Others have 2 leads, so one needs to go to ground, the other goes to the relay.

I ditched the thermoswitch though, and it's now controlled by my standalone.

well, what does the switch with the two prongs on the bottom driverside of the radiator do? that is the only thing i can think of as being a coolant temp switch.

Unless you have an automatic or a TII, you don't have a temperature switch used for a fan. You have to get your own, and find a mounting location.

Read post #18. It is related to the relief solenoid and the 3000 RPM start up function, and it switches at only ~65F.

Yes. Use one meant for an OEM application.

the radiator is originally from an s4 and it had the cooling fans on it. that is why i am asking these questions and getting more and more confused. i went to napa and they looked up the temp switch for me and it pulled up an exact picture of the switch in the lower driverside of the radiator. the one prong switch is a sensor, not a switch. how about this, ill hook it all back up and try to connect it to the one on the radiator and ill let everyone know what happens then we can go from there. i just dont want to do alot of work to try to get this fan to come on automatically if you get my drift.

?

The lower driver's side is a switch, it's for the cold start assist feature. Like was mentioned above, it closes below 65deg. The one on the top of the radiator is the low level alarm. The one behind the thermostat is the sensor for the ecu. The one on the block below the oil filter pedestal is the sensor for the temp gauge, and the only one that should be left is another one on TOP of the thermostat housing. It's a single spade terminal switch for autos or turbos with the little factory push fan. If there's another switch that you have, then post a picture of it.

Wire colors are terrible indications that you've wired it up properly. You need to look at the relay terminal numbers. 85 and 86 are the terminals for the "electromagnet." So put +12v on 85 and 86 will go to the switch. Then 87 and 30 are for power and load, so put +12v on 30 and the blue fan wire will go to 87. Then ground the black fan wire. Then at the switch, if it has 2 wires run one to 86 and the other wire to ground.

(This is for future reference, if anyone searches this thread for answers. I see you've already gotten the wiring figured out.)

:facepalm:

Ok, we'll try this again. Yes, the thing with 2 prongs on the bottom of the radiator is a temperature switch, but it's not for a fan. The guy behind the counter at NAPA has no information on what the switch is for, or what temperature it switches at. One prong connects to a wire running to the ECU, and the other runs to ground. It closes the circuit and grounds the wire to the ECU at about 65F. If you use this switch with a fan, it will pretty much run ALL the time. You might as well hook the fan up to constant power and ground if you're going to do that.

READ the thread Arghx posted in post #2. It has a gigantic picture of the single prong temperature switch that is used for fan switching. This kind of switch grounds through the body of the sensor.

The single terminal switch is easily the most common but does have disadvantages in certain situations.
Since that kind of switch grounds through it's body, you can't use sealant or PTFE tape on the threads.
Two terminal switches (called "floating ground" switches) run power in and ground out, so they're not dependent on the switch body for the ground and are handy for switches mounted in rad hose adaptors or if you need/want to use thread sealant.

When choosing the trigger temp of your switch, remember that the thermostat isn't fully open till 192°, so anything less and your fan and thermostat are constantly at war. Given the inherent inaccuracies involved, I like 195° as the low speed trigger temp and that's worked out quite well in Denver's moderate climate.
A hotter climate or smaller radiator than mine (Godspeed) might need a lower threshold trigger to be effective.
Basically, my goals are to have the fan run as little as possible while keeping coolant temp below 200°.
In wintertime, my fan rarely runs and coolant temp stabilizes @180-185 (with the heater set to full HOT and blower ON).

ok. so i pretty much need to find the one prong temp switch and locate it in the hottest part of the cooling system.

dont go from the thermosensor on the bottom driverside of the radiator. it doesnt give you the best reading for the temp of the coolant in the engine itself. this is where i first ran my wiring for my efan and even though it works it doesnt come on like it should if you were to run it off the thermoswitch near the thermostat. here a diagram of how i wired mine and it now works great

like i said it will turn on your fan from the switch in the radiator but you should use the thermoswitch on the back of the thermostat housing.. take it from my experience