DaleClark's all about fan control and the fan system
#26
I bought the sensor that Pettit sells and all last year my car would run for ten minutes after shutting it off. I finally talked to Cam and was told to remove the 2 jumper harnesses which solved that problem. It turns my fans on at 88 deg. C and my car stays cool for the most part without any trouble. I was wondering though if anyone else knows anything about this sensor, is it as good as the FC switch? I'm curious if the FC one would offer any benefit to me?
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#27
RX-7 Bad Ass
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Sounds like they have a lower temp thermoswitch. The nice thing with the FC thermoswitch is it plugs right in, uses the same connector and everything.
Wonder where they're getting their switch from...
Dale
Wonder where they're getting their switch from...
Dale
#28
Could you run the fans at High all the time? Sure. The car will take forever to warm up and use more fuel, the alternator will be loaded down running the fans, and the life of the fan motors will likely be reduced. Your car will also sound like a giant fan all the time. That's a ghetto way to do it, use the fan control system to your advantage.
What fails in the fan system? It's generally pretty robust. I have seen bad fan relays before, that's an easy fix. The fans themselves are very hardy, I have seen ones damaged by battery acid and foreign object damage. The wire to the fan thermoswitch connector can break off, causing the thermoswitch to do nothing.
What fails in the fan system? It's generally pretty robust. I have seen bad fan relays before, that's an easy fix. The fans themselves are very hardy, I have seen ones damaged by battery acid and foreign object damage. The wire to the fan thermoswitch connector can break off, causing the thermoswitch to do nothing.
First set were probably the original set with 123k miles. I bought the second set used so no idea on mileage.
85* to about 99* C is a pretty normal operating temp range for most cars. On my previous FD with a SMIC setup that allows the radiator to get good airflow, fans were OK at 130k miles.
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#31
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I bought the sensor that Pettit sells and all last year my car would run for ten minutes after shutting it off. I finally talked to Cam and was told to remove the 2 jumper harnesses which solved that problem. It turns my fans on at 88 deg. C and my car stays cool for the most part without any trouble. I was wondering though if anyone else knows anything about this sensor, is it as good as the FC switch? I'm curious if the FC one would offer any benefit to me?
#32
Well like any thing else, money spent on the cooling system is a must. My car has pretty good duct work, a M2 Large SMIC, Fluidyne Radiator, Water plus Water Wetter, and PFC set at 85C. It's getting around 100F here in FL on the pavement, about 93F ambient and I can drive in stop & go traffic at about 83-86C. Highest temp I've seen is 91C.
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#33
Recovering Miataholic
Which Sensor is Which?
Which of the two sensors in the attached picture is the one that sends coolant temperature to the PCME, and which is the fan thermoswitch? This info is in neither the 1994 factory manual nor the 1994 parts catalog. Both part numbers are shown, but identification of both parts is the same! I have the FC fan thermoswitch on order, but would like to know which sensor I will have to replace.
Thanks!
Thanks!
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Which of the two sensors in the attached picture is the one that sends coolant temperature to the PCME, and which is the fan thermoswitch? This info is in neither the 1994 factory manual nor the 1994 parts catalog. Both part numbers are shown, but identification of both parts is the same! I have the FC fan thermoswitch on order, but would like to know which sensor I will have to replace.
Thanks!
Thanks!
the other one is for the fans
#36
RX-7 Bad Ass
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It will also be obvious to you when you have the new sensor in your hand.
The fan switch is the lower of the 2 sensors with the black, 1-wire plug going to it.
Dale
The fan switch is the lower of the 2 sensors with the black, 1-wire plug going to it.
Dale
#37
Awesome write up.
If anyone needs an electric fan I would recommend the Altima or Taurus fans. Those push big CFM's and are known to work much better thahn aftermarket fans.
And can be found at many junk yards.
If anyone needs an electric fan I would recommend the Altima or Taurus fans. Those push big CFM's and are known to work much better thahn aftermarket fans.
And can be found at many junk yards.
#39
Recovering Miataholic
mefarri,
No, only the lower one needs to be replaced. The upper one (green connector) sends coolant temperature info to the PCME, which sets A/F ratio, and also can change fan speed (I think), but it is set correctly for the FD.
No, only the lower one needs to be replaced. The upper one (green connector) sends coolant temperature info to the PCME, which sets A/F ratio, and also can change fan speed (I think), but it is set correctly for the FD.
#40
RX-7 Bad Ass
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Those cars have clutch fans that are always a pain - in the way, rob engine horsepower, etc. Guys have looked for all sorts of alternative fans.
Again, the STOCK FAN WORKS GREAT. I can't see any reason why you'd use an Altima or Taurus fan.
Dale
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I have done the FC thermoswitch modification myself and I have a few questions....
I noticed while cruising, im getting 180 degrees, and when I really get on it the highest temps I got are about 190-200 degrees F. Does that sound normal? If my car is running at 180 degrees, wouldnt I still be in closed loop and my ecu would think my car isnt warmed up and itll dump more fuel and make me run rich? I have an OEM thermostat.
I hope thats not true because I need to pass smog so im wondering how this switch will affect smog. I read someone on here who has the FC thermoswitch on his FD and passed smog running the engine only at 180 degrees , but he had an aftermarket thermostat that opens sooner too. do I NEED a thermostat that opens sooner to make this switch operate efficiently or.. I just wanna know how all this works
I noticed while cruising, im getting 180 degrees, and when I really get on it the highest temps I got are about 190-200 degrees F. Does that sound normal? If my car is running at 180 degrees, wouldnt I still be in closed loop and my ecu would think my car isnt warmed up and itll dump more fuel and make me run rich? I have an OEM thermostat.
I hope thats not true because I need to pass smog so im wondering how this switch will affect smog. I read someone on here who has the FC thermoswitch on his FD and passed smog running the engine only at 180 degrees , but he had an aftermarket thermostat that opens sooner too. do I NEED a thermostat that opens sooner to make this switch operate efficiently or.. I just wanna know how all this works
#42
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Ernesto13B, do your temps go above 200 if you simply have your car idling, it should unless it's cold (say under 50F) out? According to Dales info the FC termoswitch will make the fans come on when your coolant temps hit 97C (around 207F) rather than 107C (around 225F). So long as your car is running properly, you should pass, if you're worried that your temps are too cool, simply idle it to get the temps above 200 before pulling into the testing station...
#43
Recovering Miataholic
Agree with f2racer.
Also, according to my 1994 RX-7 workshop manual, page TD-4, the stock thermostat begins to open at 80.5 - 83°C (177 - 182°F), and is fully open at 95°C (203°F). Those temperatures are independent of whatever fan switch sensor you use. So in normal (moving) operation, when fully warmed up your thermostat should hold your coolant temperature between 177 and 203°F. The 207°F fan switch for the FC won't affect that; it just means that if temp rises above 207°F that switch will turn on the fans. (BTW, the stock Miata fan switch also trips on at 207°F.)
Also, according to my 1994 RX-7 workshop manual, page TD-4, the stock thermostat begins to open at 80.5 - 83°C (177 - 182°F), and is fully open at 95°C (203°F). Those temperatures are independent of whatever fan switch sensor you use. So in normal (moving) operation, when fully warmed up your thermostat should hold your coolant temperature between 177 and 203°F. The 207°F fan switch for the FC won't affect that; it just means that if temp rises above 207°F that switch will turn on the fans. (BTW, the stock Miata fan switch also trips on at 207°F.)
#44
Full Member
Very nice writeup.
IMHO, running the fans when the engine is off will not do a very good job of cooling down the engine. Without the water pump spinning, the coolant in the radiator gets cool but the coolant inside the engine stays warm (usually gets hotter due to lack of coolant flow). Anyone with an aftermarket water temp gauge should be able to check this for themselves... turn the key back on after a couple of minutes and observe the water temp, then start the engine and let it run for about 30 seconds and watch how the coolant temps drop.
I suppose there may be some benefit in removing some hot air from the engine bay, but I suspect a better solution would be to open the hood (or install a vented hood) if you are concerned with engine bay temperatures. Personally, I don't like the additional drain on my tiny aftermarket battery.
IMHO, running the fans when the engine is off will not do a very good job of cooling down the engine. Without the water pump spinning, the coolant in the radiator gets cool but the coolant inside the engine stays warm (usually gets hotter due to lack of coolant flow). Anyone with an aftermarket water temp gauge should be able to check this for themselves... turn the key back on after a couple of minutes and observe the water temp, then start the engine and let it run for about 30 seconds and watch how the coolant temps drop.
I suppose there may be some benefit in removing some hot air from the engine bay, but I suspect a better solution would be to open the hood (or install a vented hood) if you are concerned with engine bay temperatures. Personally, I don't like the additional drain on my tiny aftermarket battery.
I've seen so many people say so many different things for shutting the car down I never know what's right. One of the things I read is to let it sit for a bit, then start it and let the coolant cycle and then shut it back off. Is that worth doing or is that just another personal preference? I just don't like the idea of having 100C fluid sitting there.
As it is, the fans in my car are set to come on around 85-87C and it runs pretty cool. It gets to 95C a couple times but never for that long, usually it's 88-90 with the recent hot and humid days.
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Ernesto13B, do your temps go above 200 if you simply have your car idling, it should unless it's cold (say under 50F) out? According to Dales info the FC termoswitch will make the fans come on when your coolant temps hit 97C (around 207F) rather than 107C (around 225F). So long as your car is running properly, you should pass, if you're worried that your temps are too cool, simply idle it to get the temps above 200 before pulling into the testing station...
I will def take your advice and warm the engine to 205 when I do the test, thanks!
#46
On A Boat
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Great write up Dale . More stuff added to my list to do to the car this summer while I have it taken apart.
and jmadams, thanks for that input as well. I'm assuming I have the problem you are speaking of since my AC turns on and off randomly no matter what setting it is on.
This thread is full of great information to help solve multiple issues. keep it coming!
-Justin
and jmadams, thanks for that input as well. I'm assuming I have the problem you are speaking of since my AC turns on and off randomly no matter what setting it is on.
This thread is full of great information to help solve multiple issues. keep it coming!
-Justin
#47
On A Boat
iTrader: (16)
Sorry for the double post, but I'd also like to point out that Pettit makes a thermoswitch that kicks on at 85C! So if you're looking for ultimate cooling this might be the best option. Oh and it's also plug and play just like the FC one.
http://www.pettitracing.com/rx7/index_cooling.htm
-Justin
http://www.pettitracing.com/rx7/index_cooling.htm
-Justin
#49
Recovering Miataholic
Since the stock thermostat begins to open at around 82°C and is fully open at 95°C, using a fan thermoswitch that cuts in at below 95°C does not make sense, IMHO.
#50
RX-7 Bad Ass
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Thermostat temp is really around 82 deg. C. The car should warm up, hit 82, and stop. That's what mine does most times in nice weather. 82 is a very comfortable engine temperature.
I do agree that a really low fan switch is a little weird. I prefer to have the fans slowly come up in stages. But, if you have a stock ECU, that might be worthwhile.
Would be interesting to find out what fan switch Pettit is using . I'm sure you can get it cheaper elsewhere.
Dale
Dale
I do agree that a really low fan switch is a little weird. I prefer to have the fans slowly come up in stages. But, if you have a stock ECU, that might be worthwhile.
Would be interesting to find out what fan switch Pettit is using . I'm sure you can get it cheaper elsewhere.
Dale
Dale