Well I though I would share me experience for the location I decided to try for a Painless Wiring thermo switch.

On the back of the thermowax there is a thermo vacuum valve that is used for the 2ndary choke plates as I call them. I removed that vacuum valve and threaded in the thermo switch. Threaded in perfectly except it leaked a little. I was going to try Teflon tape to stop the leak but first I though I would see how the thermo switch reacts to the temps at that location.

The switch is ON at 200 and OFF at 180.

While the engine is idling, I waited for it to reach 200. The fan turned on at exactly 200. I was very impressed. While the temps started to drop, the engine temp at the thermostat reached 176 degrees and actually a little lower. The fan was still on. I waited for about 1 minute after the temp reached 176 and finally the fan turned off.

So, I need to try it in a diff location and im thinking of just sticking it in the top rad hose since I know that would work. So possibly, I guess we can rule out those small hoses that run from the rear housing, to the thermowax, bacv and back to the WP housing.

Now that im thinking of it, this same location may not be real accurate for a temp gauge either.

Remember that I have not ruled out a bad switch though.

Figured I would let all you know for the future.

 

It seems crazy to me to have a switch operate over such a wide range. A hysteresis of <10degF makes much more sense and that's how most OEM temp switches work. The fact that it's not adjustable is another reason I'd look for a better switch.

Do you have a thermostat? Are you sure it's working properly? The thermostat should prevent the engine temp dropping below 180degF.

 

The thermostat has been in for about a year and it should be working fine. I also found this to be a little odd but I figured it may have just been the cheap thermostat not being very accurate at when to completly close. Since it reached only to about 176, I would say the thermostat is working, just not very accurate.

I don't like adjustables, and for me, why would I ever need one. Most of them have a probe you push through the rad, unless you have a PWM switch or something to allow you to adjust the On Off temps with a thread style switch.

Switching on a 200*F is perfectly fine. Since the temps drop to 180*F pretty quick, the fan will not be on very long and the engine would have to slowly reach up to 200 again. If the range was shorter, the fan would turn off and on more frequently.

 

So you're not using an OEM thermostat...

I'm sure they're available in a variety of styles. I had one that had a probe that went into the upper radiator hose.

If/when I use an e-fan I'm going to use this voltage switch to trigger the fan from the ECU thermosensor signal. It has adjustable trigger point and hysteresis, and I don't have to mess with installing a temp sensor.

And there's nothing wrong with that. Watch an OEM e-fan some time.

With an OEM thermostat and fan, my engine temp never drops below 84degC/183degF once it's warmed up. So with that temp switch once the fan was triggered the engine would probably never cool down enough for the fan to switch off. Does that sound like the correct operation of an e-fan to you? It sounds like you've gotten away with it becasue you're using a thermostat that lets the engine temp drop lower than it's supposed to.

 

Right now im using an adjustable electronic thermo switch with a probe that sticks into the fins of the rad. Fan comes on at about 200 and turns off at around 185 or so. Which is where I like it. OEM fans seem to turn on much later.

Do you have a programable ECU? or Rtek or somthing to be using the ECU thermosensor signal? Tell me more about this. Im interested.

And no im not using an OEM thermostat. I find it works just fine. I would never have my efan cool the engine below 180. I would actually like the fan to turn off at around 185-190.

 

So what happened to the non-adjustable switch you started this thread with a week ago? And what about "I don't like adjustables, and for me, why would I ever need one."

I'm not referirng to when they turn on, but how long they run for. The hysteresis is not 20degF like your switch.

I have a stock ECU with a stock thermosensor. That's all you need for that voltage switch.

You're contradicting youself again. Before you said "Since it reached only to about 176, I would say the thermostat is working, just not very accurate."

 

haha, am I confusing you? Sorry. The adjustable I have had for about 5 years now, but I don't like it at all. Mainly how messy it looks and the adjustment keeps moving on me. The non adjustable I still have I just need to find a diff place for it. I have been to busy to try anything new.

Ah ok. They shorter? Like 10 degress instead of 20?

Is it the thermoswitch on the back of the water pump housing? Im looking into that voltage switch now, I could actually use that switch for different things too. Great Find!!!! I may go that route. Seems like a MUCH BETTER way. No need to find a location for the aftermarket thermoswitch that I now probubly wont use.

What im saying is that I would not want my fan to cool the engine past 180. Since the location I had the thermoswitch in did not allow the thermoswitch to react quick enough and allowed the fan to run untill the engine reached 176 +/-, I will have to find a diff location so the thermoswitch can react quickly and the engine temp does not get that low.

Im still interested in the ECU thermoswitch idea.

 

Granted they are not usually pretty things, but they should definitely not move once set. The last one I used was adjusted only one and then never touched for over four years.

It's a thermosensor as opposed to an on/off thermoswitch. The voltage the ECU sees varies as tamp varies. The voltage switch I linked to is tapped into the ECU's signal wire and uses the changing voltage to trigger an onboard DTDT relay. The circuit also has adjustable hyteresis, so you can accurately see both the on and off temps for your fan or any other device connected to it. And like you say, no new sensor required. Pretty good for less than $25 and an hour with a soldering iron.

 

Some Rx7's have a relayed thermoswitch for the front mount pusher fan.
Why not use just the OEM switch? and location?

Mazda used 2 different temp ranges depending on switch PN.
207F turn-on 194F turn-off, and 195F on and ??? off.

http://www.mazdatrix.com/86-92Electrical-Engine.htm

 

Ya I think im deffinatly going to go this route. Really appriciate you let me know about this. Worth the money all day long especially when its less then 25. Although It seem sthey are over seas so I may have to pay for international shipping, still, not bad.

I did some research on this circuit a while back because I was just going to run the fan on the OEM circuit but it seems there is a control box that you need that I don't have. I am running the fan on the 19 year old OEM relay though Does that count?

I believe the temp switch was on the top of the thermostat cover. I have a Tstat cover with the threaded hole for the switch.

Ya you would think. Now this is most likley because the probe is in the fins of the rad. So the outside air may change how long it takes for the coolent temp to travel up the wire to the circuit. Also the probe likes to move out of the rad. This is a simple fix though, just been lazy.

 

Actually, as per the FSM, its just -12v at 204deg or something like that. You could just hook that up to a relay and power your fan. So, if "control box" means 20-30a relay.. then.... go to radio shack and get one. Hehe.

 

hmm interesting. Ya I don't know what the "contorl box" has in it. O Well.

 

NZConvert, I am going to put up on the GV site the idea you told me about using the thermal sensor. I would like to give the credit for this idea to you, basically it will say, "This was brought to my attention by NZConvertible on Rx7Club". I can type it up or if you want you can add it to this page under "Using the OEM thermal sensor" and give your self credit for it.

http://howto.globalvicinity.com/gv_w...co=1&vi=2&pr=1

Ya?

 

Feel free to do that.

 

Aight.

 

Ok NZ, I put the information up here and also how to wire it up on a S4
http://howto.globalvicinity.com/gv_w...=148&co=1&vi=1

Where can I find a S5 wiring diagram? The FSM over at TeamFC3S doesn't seem to have one.

I would like to add to the "Pin location" image I put up, the location of the S5 pins on the ECU and would also like to know which PIN and wire to splice into on the S5.

 

Well I found the wiring diagram for the S5 and what pin on the ECU the wire is on. I just don't know what color the wire is. I will have to find that out next.