Hi, I'm a complete noobie to RX7s but pretty handy with cars in general. I just got an 88 nonturbo with a friend and we're stripping it for the track. We'd like to keep it street legal at least for a little while but eventually we might do an LS1 conversion and really go nuts with it.

Anyways, my question for this thread: Would a standalone efan controller like the Summit kit (or similar adjustable thermoswitch) work the same for the small blower in the heater core? We're gutting the dash when the cage goes in and we only need the heater core for defogging the windshield and maybe a little extra heat dump for hot track days. There is absolutely no need for any of the other fancy HVAC stuff, and the AC was already removed before we got it.

It seems to be almost the same exact system that we want for the heater core blower assembly under the dash: a thermoswitch with a manual override that controls a fan cooling the matrix... right?. Or am I seriously underestimating the complications of the HVAC control unit?

Any help at all will give us a head start on rebuilding the dash after the cage goes in. Thanks in advance!

 

page 15-93 of the factory service manual (body electrical section)

 

Is this diagram correct for manual switch on a S5?

 

Yes. That will toggle between "on" and "auto".... a three way switch there would toggle between "on" "auto" and "off"

 

What about those of us who have an s4 w/thermo switch or sender mounted in t-stat housing that has a 2 prong female terminal/connector (thread pitch = M12x1.5 according to RockAuto, Part #'s: TX18T, 1580134, 36413, 5S1492, F1864, TX18, and 155987 ) AND have a 2 male terminal thermo switch (thread pitch = M17x1.3 also according to RockAuto, Part #'s: TS182, 36535?) in the lower driver side corner of the radiator? LAZARUS!!

 

First off, I would like to start by stating that this thread has contained much useful information and I thank the contributors greatly. In lieu of this, I would like to pose a question here versus starting a new thread.

My problem is thus:

Currently installed on my 1988 GXL (by previous owner), are both a Koyo Rad as well as an electric fan setup. The fan is wired to a relay straight off the battery, and then directly into the green Accessory plug that is found on the S4's. That being said, the fan is constantly on. This needs to be changed.

In order to help understand this I have the following pictures:





Please note that nearly all emissions have been deleted and that there are several pre-drilled holes where AC used to be connected.

With this being said and the current set-up as it is, where would be the best place to mount an aftermarket thermoswitch? Also, with the wire configuration as is? How should I wire it.

I have read the entire thread and gained some insight. However, I would like some confirmation on this. (It was kind of confusing jumping into this car with all these mods basically half-done).

Thanks in advance.

 

With everything half-done as it is, the wisest choice you can make is to take apart the whole relay setup and redo it with a S5 thermoswitch. I would guess that the previous owner did not know the S4 thermoswitches operate backwards (breaks circuit at 195 degrees for NA/207 degrees on TII instead of making contact). This backwards operation is a pain to correct for and requires adding another point of failure (another relay) into the circuit to flip the behavior around. Much simpler to get a S5 thermoswitch.

Pin 30 to Battery+ (via a suitable fuse)
Pin 87 to Fan+
Pin 86 to Thermoswitch
Pin 85 to Ignition-switched source (with a fuse too)

If it is currently done like this, the fan will run untill the car reaches operating temp, then stay off (thermoswitch removes ground connection from relay). By killing the ignition, the fan comes back on because the coil isn't seeing 12v+ and ground anymore.

Just remember that to pass power from Pin 30 to Pin 87, you need to apply 12v+ on one side of the coil and ground to the other side. Polarity doesn't matter, just as long as pin 85 and 86 have 12v+ and ground.

Usually, the best place for an aftermarket thermoswitch is at the upper radiator hose bung where it is the hottest. You might consider removing the bleeder plug and threading in a suitable metric to NPT adapter. I believe it is M12x1.5 thread pitch there but be sure to check the Second Generation FAQ to be certain.

 

So I've read thru this whole post and here's what I've got. S4 with the push probe into radiator running a taraus efan. Also added manual switch. Can i just replace the s4 thermo switch with a s5 and rewire without the orielly push probe junk?

 

Yes.

 

Cool probably switch it. Thanks!

 

Hello Quick clarification, the Thermoswitch on the S4 is the one located at the Neck of Filler neck, but not the Thermo Sensor located on the waterpump housing near the attachment of the Filler Neck and Housing itself.

 

Well I am going to buy this
Summit Racing SUM-890016 - Summit Racing® Electric Fan Thermostat Kits - Application - SummitRacing.com

I am going to place the sensor in the upper pre drilled hole in my Koyo. One last question: In this location and a sensor that switches the fans on at 200F. Will this be close enough to the actual temp to where 200 degrees is an appropriate temp? (reason being, thermostat opens around 195 correct?)

 

thermostat begins to open at about 180F and opens completely at 203F. Honestly, I don't think the location matters all that much in real world operation.

 

So in the case of the Summit racing part, the 170* off would make the fans continue to run as well as stress the thermostat?

 

well there's no sense in running the fan while the thermostat has already closed...

 

30* is a ridiculous hysteresis. Your fan will run *always*. You might as well save the money and wire the relay directly to the ignition.

 

i have a hayden fan switch. worked for 2months. now the fan turns on then off right away when the car is warmed up. can someone help me out? the fan is fine but just wont stay running when the car reaches up to temp?? can it be that the switch went bad??

 

The fan is currently wired directly to ignition. I can see how the 170* would make the fan run constantly and retract my statement in regards to the Summit part. I am just having a tough time finding a suitable thermoswitch with a decent fan on/off temp. I would simply spring for an adjustable one, however I do not have an aftermarket gauge.

 

Here is *a* correct temp range switch, in my opinion.

Vintage Air 11205VUR - Vintage Air Electric Fan Set-Point Temp Switches - Overview - SummitRacing.com

Use the wiring diagram from the thread, use this aftermarket switch with a heavy duty relay.

FWIW, I am currently using a Summit switch that was sold as 200*/185*. It is labelled on the switch 195/175. My fan *ALWAYS* runs except in cold weather, even with a Koyo rad and a Lincoln Mark 8 fan. The temp on my manual gauge sits on the open thermostat temperature, 185*.

I am going to switch to the one I listed for a better temp range. I am using a radiator hose adapter like this:



I tapped the 1/8" bung to a 3/8" for the switch. I have the front of the waterpump tapped 3/8" for the mechanical gauge sender.

 

Searched the NAPA site and dug up this:
NAPA AUTO PARTS

I am pretty positive that this switch will seeing as it is the correct thread pitch and an appropriate temperature to kick on. However, the only thing I cannot tell is if the switch operates like a normal S5 switch. They have one specifically listed for the S5, but I will be damned if I am paying $73.00 for it. With the M16x 1.5 switch, I can just simply drill and tap out the factory location in the S4 neck.

Thoughts?

 

bumping an old-ish thread. can you just use a tap for the factory thermostat? IE:

Quick-Disconnect Adapter Set (8-Pack) : Adapter Sets | RadioShack.com

from radioshack?

Thanks.

 

what?

 

use the factory thermoswitch and use the quick-disconnect adapter set to tap it to allow for two female end wires to accept a signal one for stock harness and the other for the new fan.

 

yes

 

thanks! going to try and finish this install tonight.