Phaz

Hi ive had a look through the library cant find anything on this.

I want the fans to come on as normal when the temp peak, but i also want to fit an overide switch which will allow me to keep the fans going if i wish too, is there a write up on this or a post? cheers

Also the stupid turbo timer - having parked up and turning the car off (fans are running at this point) when the turbo timer goes off and kills the engine, it also turns the fans off not allowing the car to cool down, so put the ignition back on and fans start up again but i have to leave the keys in ignition not really safe.

Any help ideas would be great, i can take pics and vids if you need to view wiring

NissanConvert

iTrader: (1)

Do a search for "FC thermoswitch", or if you have a PFC get someone with a dataloggit a six pack to set the fan temp lower in the PFC. You could get even more complicated with it, but those are the easiest methods.

Get an undertray if you don't already have one.

Badappex

iTrader: (2)

Do a search. I know if you ground one of the fan relays (i forget which one), the fans stay on for a period of time when the car is turned off. I had it on my car but removed it when another relay went bad.

wjp005

iTrader: (3)

Here ya go:

This article documents something that I did to MY car. This document may contain errors. If you choose to attempt to duplicate this modification, you do so at your own risk.
The electric cooling fans on the 3rd generation Rx-7 don't tend to activate until the coolant temperature has become very hot. Those of you with aftermarket coolant temperature gauges know exactly what I'm talking about.
One trick is to turn the A/C on low. This will cause the fans to come on (low to medium speed usually).
Another trick is to turn on the parking lights. This will cause the ECU to turn the fans on at a lower temperature than it usually would.
My problem is that 1) my driveway is 1/4 mile long and very steep 2) I park on the top (6th) floor of the parking garage at work, you enter from the bottom and creep up to the top in 1st gear... avoiding all the idiots who think the parking garage is their own personal autocross course. Both of these situations tend to get the engine temps up just when you need to shut the engine off.
So, I rigged up a switch to activate the cooling fans, instantly. This way I can activate the fans early and avoid letting the engine temps get up.
First, a little information on how the fans work.
The fans are controlled by four relays that live on the passenger's side of the engine compartment. I will name them 1, 2, 3, and 4.
4 1
3 2
(as viewed from the passenger's side fender)
Relay 1 is connected to the heater control unit and activates when you turn the A/C on.
Relay 2 and Relay 4 are connected in parallel.
Relay 3 is connected to the water thermoswitch and increases the fan speed.
Various combinations of relay activation yield different fan speeds. There are many combinations, but these are the ones I am concerned with:
2 + 4 = low fan speed
2 + 3 + 4 = medium fan speed
1 + 2 + 3 + 4 = high fan speed
The ECU just grounds a pin to activate a given relay. I don't think it can check the state of the relays, so I should be able to activate the relays manually without upsetting the fuel computer.
So here is what I did:
Locate the relays (click the image below for a larger picture).
The set of relays can be seen in the picture above. The two relays with the colored dots on them are the relays that I tapped into.
Removing the two 10mm bolts that hold the relay bracket in place gives easy access to the wiring.
The red-dotted relay should have a GREEN/BLACK (green wire with a black stripe) wire going into it. Splice a piece of insulated 16 or 18 gauge braided wire into the GREEN/BLACK wire. A vampire type connector can be used or just strip the wires and solder them together. Be SURE that you don't cut the wires going to any of the relays. Do the same for the BLUE/GREEN wire going to the green-dotted relay. Check the wires with a voltmeter before splicing into them. If they have voltage on them under any circumstances (ignition on, off, etc.) then you have the wrong wires. There are large, high current wires in that same harness that you don't want to mess with.
You should now have two wires coming from the two relays. Now would be a good time to test them. With the ignition switch on, grounding the wire from the red-dotted relay should give you low fan speed. Grounding both wires should give you medium fan speed.
It is time to make a decision.

1.
Splice the two wires together with a single, longer wire. Run the single wire into the passenger compartment and connect it to a SPST switch (RS# 275-324b). Splicing the two wires together has the side effect that any time the ECU tries to turn the fans on, it will get one speed higher than it asked for. It will get medium speed instead of low, and high speed instead of medium. This is fine with me and that is how I did mine.
2.
You can run both wires into the passenger compartment and connect each one to its own switch, or use an single DPST switch, and the ECU will get the fan speeds it asks for when the switch is open.

In either case, the other side of the switch (the side not connected to the relays) needs to be connected to a ground.
I used a piece of convoluted tubing (also available at Radio Shack) to protect the wires running from the relays. The tubing is indicated by blue dots in the picture above. I routed the wiring through the ECU harness grommet at the firewall. The ECU harness grommet is a major pain to get to, so, in the future I will probably just drill a hole in the firewall somewhere and add a grommet.
Here is a picture of my switch, mounted next to my water temp gauge, in a home-made gauge panel.
Notes

*
My car doesn't have the fan control wiring update. If your does, you will find an additional wad of wiring in the relay areas. If you added this switch modification, I believe the only difference would be that your fan switch would work with the ignition off or on. I'm not sure about this, so proceed at your own risk.
*
My car is a '93. I'm pretty sure '94 wiring colors for the relays are the same. I'm not sure about '95s.
*
Flipping the switch mod will yield MEDIUM speed, unless the A/C is on (which will yield HIGH speed).
*
Check to see that the fans work properly with the switch off... If the relay wires were cut, the ECU won't be able to control the fans.

Thanks go to Tom Johnson for this great idea!

Taken from here:http://rx7.voodoobox.net/

RLaoFD

iTrader: (6)

Woah, no need to go into the engine bay at all. There is a loose wire next to the ECU that needs to be hooked up to a switch, and the other side a ground. Use that switch.

look up "Fan Mod" best thing to do for a car without a PFC.

Supernaut

iTrader: (83)

I have the control box to make the fans turn on at the turn of a switch. If your interested let me know. I was going to do it to mine but decided I would rather just use the AC trick and have my PFC turn the fans on when applicable.

Phaz

This is great Guys im gonna av a look tonight,

thanks for all your help

RLaoFD

iTrader: (6)

Cooling Fan Modification

Last updated: August 4, 2002

Date: Tue, 03 Mar 1998 23:38:41 -0800
From: Daegal Benedetto (dae@ix.netcom.com)

There was a thread on this subject last fall and everyone said they have never had the fans come on by themselves after shutting off the car.

However, there is a way to test the circuitry, (and that leads to a way to make a fan timer). There is a single black wire (with connector) coming out of the ECU that is not attached to anything. To test the fans you need to attach this wire to ground for two minutes while the car is running. With the wire still grounded, turn the car off and the fans will stay on. After 30 seconds, un-ground the wire and the fans switch to low speed. The fans stay on for ten minutes.

The ECU is down in the passenger side foot well. You need to pop off the door sill trim and then pop up and remove all the fasteners holding the foot well panel. Best to go slow with this as the plastic stuff will crack easily. Once the panel is removed you can see the ECU mounted to the chassis. The test lead on mine was just hanging there, toward the front, but I remember someone saying they had to remove the ECU from its mount to get it. The lead is black and has a female spade connector on it. You should test the circuit first to be sure it works. I used a male spade connector end and an alligator clip test wire. Connect it to ground for a little more than 2 minutes while the car is running. Turn the car all the way off and the fans should be running. After 30 seconds disconnect the wire from ground and the fans should switch to low speed and stay on for 10 minutes (it's timed not temp controlled).

I ended up installing a stock foglamp switch in one of the blank switch holes on the center console. (Almost any switch will work, doesn't have to be the Mazda foglamp switch at $50.) I ran one wire from the switch to the ECU test lead and the other to ground. I just engage the switch 2 minutes before I turn the car off if I want the fans to run after.

> How did you route the switch wire from the console to
>the ECU without having to pull up any extra covers or mats,
>etc.?

I didn't. Besides the foot well cover, you have to pop up the center console to mount the switch. I used in-line spade connectors at the switch end and ran 2 twelve gauge wires from the switch, under the center dash, up over the foot well behind the dash under the glove box and down into the ECU area. At the ECU end I used a male spade connector for the test lead and a ring connector which I mounted with another ground wire on the door side of the ECU.

I've had this hooked up since last September. I don't know if it cools the engine off any faster but I can tell you that the engine compartment does cool off faster which can't be bad for all the plastic and rubber in there. I only use it when it seems appropriate but have not seen any affect whatsoever on the battery.

Don't ground the wire all the time as the fans will run all the time. Be sure to allow for a cool down for the oil in the turbos.

NOT MY INFO

Phaz

that is GREAT ive already got a blank switch i fitted in my dash, and my pannels are off, ive taken it off before so its no problem for me build my rx7 from the ground up so i know every little part just needed the knowledge on what to do

A+++++++++++++++

thanks Lads