Cooling fans questions
 

What all is required to turn on the cooling fans ?
I havent done the fan mod yet, so I searched and read there is something you can do with the AC and AC relay ?

1) As I understand it, you leave the car running, and remove the AC relay, then turn on AC and fans run. Is this true ? Do they keep on running when you turn off the car ?

2) Another possibility I read about is to leave the key on the ON position (without the car running) and it will run the fans for 10minutes (someone said 60secs). Is this true ?

I also read about the wire from the ECU. I changed my ECU few months back and dont recall any unconnected wire :o:

3) To do the fans mod, you need to splice into 2 fan relays AND connect it to a ground ? Then what is that ECU unconnected wire everyone talks about used for ?

Thanks!:p:

Cruiser, get the miata thermoswitch, its a no brainer install and works great.

By the way, did you ever find that heat tape?

i did the fan mod.

basicly you splice the relay(s) for the fanspeed you want. i only wanted the slow fan speed so i only spliced one relay. its as easy as splicing one wire together and running that wire into the cockpit to a switch that is connected to a ground.

I think i got the whole write up off iluvmyrx7.com

What exactly does a miata thermoswitch do (I know it kicks in the fans soonerm but does it make them run after you shut down the car for 10mins) ?

No, havent found it yet. Looking, looking... :)

The miata thermoswitch replaces the stock thermoswich and turns on your fans automatically at 210f.

Here are some pictures of my engine bay with the heat tape. I found it at the Home Depot.

http://www.ultramarine.com/~neel/200..._4382.jpg.html

http://www.houstonrx7club.com/events...s/DCP_5356.htm

http://www.houstonrx7club.com/events...s/DCP_5357.htm

I hope that they help and give you a better idea of what to look for.

Jason

^

what is the point of running the fans if the waterpump is not spinning? all you would be doing is cooling the water in the rad. but the block wouldnt be affected correct? i dont see the point.....

I did the Dave Disney fan mod and it worked out as well as possible.

My fans run at medium speed whenever there is electric current through the car (when the key is in the "on" position). I have a switch in my cockpit that, if turned on for 2 minutes, will keep the fans running for 10 minutes after the car is off. It will also turn the fans on/off when the car is off.

Using this mod in combination w/ turning yoru A/C on will yield high fan speed and cool you down ASAP.

I would recommend it!

I did the fan mod with the wire by the ecu. You simply connect a spade connector into the existing female connector. No splicing required. Run the connected wire to a switch, and then to ground. It works very nicely. I like that I can turn the fans on when I want them on. I also like that I can run them for 10 minutes after the car is shut down.

One word of caution with this mod: If you forget to turn off the switch, your battery will run down.

http://www.scuderiaciriani.com/rx7/fan_mod.html

The point is engine bay heat. If you have been driving the car hard, and shut it down, there is a tremendous amount of heat under the hood. The water temp may be only 220, but there are other parts of the engine (turbos, exhaust ...etc) that are much hotter. This heat acts to cook everything under there. And since our cars have so much plastic under the hood, the heat can be very bad. Thats one of the reasons that we have so many problems with replacing vacuum hoses and solenoids.

Running the fans for 10 minutes after shutdown will blow all of that heat out of there, and prolong the life of many components under the hood.

Some people make the arguement that it helps the natural convection. If I am autocrossing I do it to cool the water in the radiator between runs and when the water pump starts running it really helps to keep the temps lower throughout the heat. It also helps circulate air through the engine bay to help fight heat soak. It also helps when you run into the store real quick.

It actually helps cool the whole engine bay. If I need to work on my car after driving it I do this as it helps cool down a lot of the parts and makes the car a lot easier to work on.

so what do you guys normal set your fanswitches to? i have mine wired for low speed. would wiring it for medium make a significant difference?

Does this mod also allow you to turn them on instantly when you want to ? If so, how ? (do you turn on the switch with combination of AC ?) Or is it only to cool the car down after you shut it down ?

And what is the deal with the AC relay ? You just pull it and turn on AC and fans start to run ?

The fan mod I referred to has a two minute delay. There is some very good info in the thread I posted for you. Here it is again.

http://www.scuderiaciriani.com/rx7/fan_mod.html

If you guys want to fight engine bay heat after shutdown, open the hood. This will cool far quicker and far better than running the fans.

If you want to cool your motor as quickly as possible (like between autox runs) you pop the hood, kick on the a/c to start the fans (if they aren't already running) and soak the condensor/radiator with water from a garden sprayer. Temps drop like a rock and I shut off the car at 190F. It literally only takes a few minutes to cool the car and takes suprisingly little water. It is not at all uncommon for me to start with 190F water temp and finish a run less than 60 seconds later with 220+F and then return them back to under 190F in grid all in the span of 5 mins.

Lots of people seem to feel that running the radiator fans after shutdown will prolong the life of plastic and rubber components under the hood. I don't share their optimism. Fact is right now all the underhood plastic/rubber FD components are 10+ years old; they already need replacing. New ones in there are going to last another 10 years. I don't think a few minutes of fan running after engine shutdown is going to prolong anything in there. Their environment with the engine running is 10 times worse and that is what will age them, not heatsoak after shutdown.

Those both work well. The problem is that you can't leave your car with the hood open in very many places, and people are not going to drive around with a water sprayer unless they are at the track.

I have to disagree with you on this one Damon. If the car is running (moving) there is going to be airflow thru the engine compartment. This will act in a similar manner to running the fans. The hot engine components will have air passing by. This will remove a lot of the heat from the engine bay. If the fans are running, even more engine bay heat will be blown out.

The only time it would be worse is when you are stuck in traffic, and the fans have not come on yet.

And every single other time the engine is running regardless of car or fans moving. Simple experiment: Go drive down the highway for 15 mins and then pull over to the side of the road and raise the hood. Stick your hand in there and attempt to grasp anything anywhere under the hood for more than a couple seconds before your flesh begins to burn.

It didn't instantly get hot in the few moments you pulled the car over and quit moving; it was hot the whole time. Sure you've got a 70mph breeze coming through the inlet when on the highway. Does that mean all the parts under the hood don't get overly hot? Heck no.

Like I said, running the fans here and there after shut down isn't going to help the problem. Everything is terribly hot anytime the engine is running. A few minutes of fans running after driving the car for anything more than a few minutes isn't go to do anything for the life of the components. You can cool the car slightly quicker, but you're not going to add any life IMO. What kills rubber and plastic is the heat cycles from very high temps back to outside temp. Running fans isn't going to help this.

There are different degrees of heat that you will find under the hood, at different times. With no airflow thru the engine compartment, everything will be hotter. Sure, its still going to be hot under there regardless of what you do. I would much rather have my engine bay 40-50 degrees cooler by running the fans. And yes, I believe that will significantly extend the life of many components.

IMO it's like fighting a forest fire with a garden hose. Does it help? Yes. Does it do anything meaningful in the scheme of things? No.

The plastic and rubber don't care if they are a little hotter than they would be with the fans running after shutdown. They've already (literally) been through hell when the engine was running.

You may not be able to put out the fire, but if you are able to keep it away from your house with a garden hose, you have saved your house :D

I think that the engine bay gets a lot hotter when the car is stopped, and no air is going thru. Robert Kinports did some tests, and posted temp readings. They are on the fan mod thread I posted earlier.

Thanks, I read that 2 times already :p:

Today I pulled my AC relay and turned on AC on level 3 and fans turned up. VOILA !

I'm going to a drag race compeition tomorrow in Croatia so I will need every little bit to keep my temps down.

After driving continuously, I can open the hood and fully touch the UIM with no excessive heat issues.

As soon as my WB and fucking datalogging ever gets here I'm going to do a thermistor test of just what is going on under there.

Hey you got it. I would have told you that earlier, but I just now saw this thread. Like you already found out all you have to do is pull the A/C relay. After you pull the relay you simply push the A/C button inside your car and turn on the air as if you were hot inside the car.

The trick with this is that your can now ran your fans whenever you want for as long as you want. Then if you want you can turn off the car and then just turn the ignition switch back to on and run the A/C like before.

By pulling the relay all you really do is keep the compressor of the A/C from running, which means you can force the fans to come on without the extra power draw that the A/C would usually create. This is a simple little trick that is very useful to know.

- Cody