Okay, I am sorry for being a noob at this.

After I read Dale Clark thread, decide to go install an fc thermoswitch, so I order one from Ray at Malloy Mazda,
PN 41-18-840.

Please look at the pictures below, my stock thermoswitch is on the left. The sizes are different. The fc switch will not fit the whole behind the coolant neck filler.

Please help.

Is it because my long block is a jdm?

 

Make sure you're taking out the fan thermo switch and not something else. I had to take off the water pump to install it, but I think it can be done without removing it. I'm fairly certain the stock thermoswitch looks just like the FC so I think you may have taken out the wrong sensor. Even my pettit fan switch had an o-ring on it.

 

+2
You pulled the wrong one out.

 

Haha. The thermo switch is black and looks exactly like the grey fc switch. It is directly under the green coolant temp sensor.

 

Thanks guys, i realize my mistake when I did more research but trust me, that water housing is a jdm one, so there is no thermo switch on the bottom of that sensor. So I have to create one , I attached the fc switch to the coolant neck below. Is that okay? (Plus the previous owner cut that that sensor wire, luckily I was able to find it on the harness)

 

You won't see it until you take off the water pump. I would not put the sensor where your circled. Put it where it is supposed to go on the waterpump.

 

^you read what I said right, there is no sensor below the green connector I have above. I double check it with my friend 93 r1 right next to me. The previous owner did a jdm swap and use the jdm water housing.

 

later jdms didn't had that sensor.Either find a used usdm water housing or drill and tap the jdm housing below the one you already have.

 

Yep, you have a later JDM water pump housing that doesn't have a hole for that sensor. Mazda figured out instead of having 2 sensors they could just do it with 1.

Do you have the original '93-95 wiring harness/ECU in the car? If you do, you'll have a plug for the sensor. In that case, swap out to the earlier US water pump housing and you'll have the hole.

Without that sensor you'll have weirdness with your fans, that input for the fans is totally missing. Unless you're running a '96+ harness and ECU, which would have been a bitch to swap into the car.

Dale

 

dale is your site ever going to be back up?

 

I guess Mazda did the same thing to the JDM RX-7 that they did to the 1994+ Miata. They dropped the 1990 - 1993 fan thermoswitch and used the coolant thermosensor plus new circuitry in the ECU to provide a turn-on signal for the fans.

 

I just bought the Pettit thermoswitch for my 2002 FD, am I reading this correctly that I will not be able to use this switch???

 

Thank you Dale for the great info. I recently swap out the old harness and replace it with a 94 manual one I bought from a board member. The harness i have right now is missing a connector for the fc fan switch sensor. I trace the wire on the harness to a hanging wire that is color red/black, is this the correct wire?
I am receiving a usdm water pump and housing tomorrow, will swap it in and see if it works.
How do I check if the fc fan switch is working once I connect it? I only have the stock water temp. gauge.

 

if you had a pfc you could of just had the fans kick on at a lower temp instead of buying the switch sensor.

 

The FC fan switch should close at 97°C (207°F). You will notice that the fans run after ignition cutoff much more often than with a stock USA FD thermoswitch, which closes at 107°C (225°F). Since the temp gauge has a relatively flat region at about halfway up the scale, I don't think you would notice much difference by looking at it.

 

That's not really the same. the ECU controls the #2 and #4 relay, the thermoswitch controls the #3 relay.

 

damn, i dont know, how i can delete my post....

 

If in doubt, here's a clever trick I discovered that you can use to identify the old switch's characteristics. I used this to make a calibration file for the FC's Intake Air Temperature sensor for my Haltech.

Using a multimeter set to ohms (preferably a digital one), connect one lead to the switch's connector terminal and the other to the tip that is normally in the coolant stream in the WP housing. You should see Infinite Ohms of Impedance/Resistance, AKA no continuity/switch is OFF.

With a common meat thermometer found in your kitchen, heat both the switch's tip and thermometer probe with a hair dryer. The meat thermometer is there to tell you the current temperature that the switch is seeing. As you are doing this, watch the multimeter for when it registers continuity (ohms go to ~0.07). When it does this, look at the thermometer. If it is indeed a FC fan switch, it will do this at 97 degrees Celsius/207 Fahrenheit.