I'm sure it's an OEM switch off another car. The factory fan switch thread is M16x1.5 . It might be a Starion switch http://www.partsgeek.com/gbproducts/...ek+Google+Base (don't remember the exact trigger temp on the Starion though) which is I believe a direct replacement in terms of the thread pitch. It uses a spade connector like the series 4 FC thermoswitches.

 

The FC thermoswitch doesnt affect or lower highway temps does it? From my understanding it only kicks in if the engine gets hotter then 205 degrees. Which means when ever the engine is below 205, it would perform the way it normally should right?

 

No, it doesn't... see post #43 above. The engine coolant would normally be between 80 and 95 degrees C, as long as enough heat is being transferred out of the radiator due to forward motion of the car. With the car sitting still and idling, no air moves through the radiator unless the fans are running, so coolant temps rise until the fans are triggered.

 

I replaced the fan thermoswitch a couple of days ago. Only one problem... in the process of aligning the wire harness connector with the new FC thermoswitch connector, the wire snapped off the harness connector, flush with the rear of the connector, i.e. no wire showing at all. The breakage was caused by the hardened harness sleeving forcing a sharp bend in the wire, as I moved it to the rear to clear the back of the thermoswitch connector. So I had to remove the pressed-in plug at the rear of the connector (difficult) which chipped out a section of the connector plastic, and then had to remove the female connection clip from the connector body (broke off a locking tab), and then splice a new wire onto what was left of the old wire, and then push the clip back in from the rear of the connector, and then pot the rear of the connector with epoxy. Since the connector was facing front down during the epoxy cure, the epoxy ran down into the female connector, filling it. About 2 hours after beginning of cure, I noticed this and picked out the epoxy from the receptacle with a safety pin point; that took about a half hour.

For anyone else doing this mod, you should know that the alternator, the coolant hose above the two stacked thermo sensors, two vacuum hoses, and the upper (ECT) sensor all have to be removed to allow access and wrench clearance to the fan thermoswitch. And some coolant will be lost... not enough to warrant draining the coolant, but maybe a half pint.

I hope the results will be worth the effort.

 

anybody running the RE-medy water pump by mazmart?

 

I am, and afgmoto1978 is also.

My FD also has the Mazmart thermostat. I've tried several times to get one for afgmoto1978 as well, and have had no success.

There were a number of mods made to my car at one time, so it is difficult to say just how effective any one of them is. As a whole, my car stays pretty cool.

I've autocrossed it in 96f weather, and oil temps (at the pedestal) are not exceeding 210, water temp (at the t-stat) also about 210.

These are the temps after running hard in 2nd hear for 50-60 seconds, and then stopping.
Considering there is no airflow at this time, I think it reasonably good.

If the temps start to creep up when parked, opening the hood cools it back down.

Cooling mods: V-mount,intake, intercooler all ducted. RE-medy water pump and tstat. Dual pass Koyo rad. Vented hood, dual 19 Row oil coolers. Also running water injection.

Also replaced a failing radiator fan motor.

I've only done one track day since doing all this. It was a cool fall day, and the first run the car simply didn't get warm - I could have used some blocking in front of the rad.

Final run air temp was 70+ degrees and the FD would get up to temp and that was about it.

 

stupid quick question, when installing the fc thermoswitch, will coolant spill out when you take the old one out? or does coolant not reach that at cold temps?

 

It's been years since I changed mine (w/the engine in the car) but IIRC there will be some coolant loss. If you have a syphon bulb and it's an issue for some reason, you can probably minimize it.

 

I have the Pettit fan switch. It switches on when my VDO gauge says about 175 deg. f. It's supposed to come on at 185 so either it's coming on early or my gauge is telling me a different temp than what is in the water pump housing. The gauge sensor is tapped into the TB coolant line. It seems like it's coming on a little early. I hope that it is only coming on low. I wish it would come on about 190 and keep it around there. After reading this thread I'm concerned that the car is always running rich since it never really gets past 190 when I'm just driving normally. Maybe I need an FC switch.

 

I just talked to Cam at Pettit and he said the TB coolant location is going to read cooler than where the fan switch is located. I guess it's coming on at 185. He recommended moving the sensor to a more accurate place on the passenger side near the thermostat housing, said there is a 3/8" plug in place. I am at work so I'm not sure where he is talking about. Anybody know?

 

Anybody know the amp draw at full power? I'm about to yank all the relays, thermo switch, and anything that I feel is unnecessary for my setup and replace it with a "simpler" setup.
I'm just going to have my EMS click a relay for each fan for full power and have my AC run them at low power, skipping the whole thermoswitch business. Looks like I'll still be running 4 relays though.

 

the water temperature on my power Fc is usually around 80 to 90......recently, the reading are wrong, its nut going past 60, and is increasing in long interval from 44.....i am assuming some sensor is bad, any thoughts???

 

Unless it's wicked cold down in the Islands , I would think the wiring is messed up. Check the connector and follow the wiring back to the main harness to see if there are any breaks in the wire insulation.

 

I have found that the water temp sensors do go bad after a while. Check the connector and while you're in there, replace it. Honestly you could probably get one from an auto parts store but they aren't that expensive from Mazda either.

 

You also could have a stuck open thermostat, if it's open the car will take much longer to warm up.

Dale

 

thanks guys, i would see if i could use these ideas to solve the problem.....thanks again!

 

Presently into removing the fan mod; pics below. No trouble under hood, but in the cabin, one black/yellow wire connected to the Fan Control module connector and another terminating in a single-terminal connector, also black/yellow, run together back to the large harness under the metal guide. This captivates the fan mod harness to the car (bad news). I presume these wires can be cut, since both are open on the fan mod end, but don't understand how they could be part of the mod and also part of the car! Does anyone know where the other ends go in the car? The single-terminal wire is the "check connector" per Dale, and the other is an unknown signal at the Fan Control module connector.

 

Right two pics above are incomplete. Found the missing fan mod cable... picture of complete wiring set is attached. Reconnecting the white-to-white OEM connectors is not easy. The cable with white connectors ran behind the metal wire harness guide, which I could not remove after removing its mounting nuts, due to interference of its flange with another large rigid plastic piece. After getting it out, I used long bent-nose pliers to hold the free-floating upper connector while pushing up on the lower one. It did finally click into place.

 

I totally disagree with removing the FAN MOD as it does allow for more cooling when needed.
Why remove a good option that is even beneficial today.

All of my PFC fan temp settings are set at 86C. My radiator is a Koyo N "3" pass.
My IC is a mid front mount Blitz. I have the 95 engine harness.

Even here in Houston during summer in stop and go driving with the AC on, fan speed three would only come on at 107C. To prevent this and help the AC, the fan mod turns on fan speed 3.

Thus my water temps only go up to 90C and stop. Even in cooler weather having the fan on 1 extra speed helps to cool the front mount IC more.

It is easier to keep engine temps down to a target temp then to get hotter and try to cool back down to the target.

Sorry but removing the fan mod is stupid!

 

In our case, removing the fan mod saved the RX-7's battery. The relatively small time we drove the car vs. the 10-minute fan ON times after shutdown could not keep the battery charged. But, I would not recommend removing the fan mod unless the Water Thermoswitch is also replaced with the FC's 97°C switch.If that is always true, the fan mod is doing nothing at all.

 

Chuck, I think you're misunderstanding the fan mod that's removed. All that does is run the fans for 10 minutes after you shut the car off, that's it. Kicking the fans on at lower temps is hugely advantageous and is the primary thought at the start of this thread.

Dale

 

i have an fc thermoswitch, from what im told, considering im running the power fc, that its useless? since the pfc already opens it before the thermoswitch?

 

After all the FDs I've had I have never heard the fans running after shutdown.

 

The thermoswitch and the PFC control two different things. There are 3 fan inputs corresponding to three fan speed "steps":

1) ECU
2) Thermoswitch
3) A/C switch

The ECU switches one input at whatever the computer is set to. On the factory ECU it's 105C, on the Power FC it's whatever you set it to. The thermoswitch bumps the speed up further at whatever temperature the switch is rated to. The A/C switch also bumps up the fan speeds. These inputs all work independently of each other. So if my ECU enables the fans at 85C, they are on low speed. Then I turn on the A/C, so they are on medium speed. Then my temps reach 97C and an FC thermoswitch bumps it to high fan speed.

 

FYI:

If you look at the fan motors you will see 4 wires going into each.

Black = Ground
Blue = Low
Green = Medium
Blue + Green = High
Yellow = Ground