how to test cooling fans
 

I'm having some overheating issues...i have the remedy water pump and radiator installed so i most definitely should not be getting to 209F in 20 degree ambient temps...i have a autometer digital temp gauge installed, the car runs around 180-185F while driving which is good but when i stop, within 4 mins its climbing fast, the highest I've let it go is 209F and this is happening at 20 degree ambient temps. I'm thinking this has to be due to one or both of the cooling fans not working. So i need to figure out how to confirm that they are working..how can i do this?

easy - fan 1 should come on at 209 so just sit with the car idling until you see 209 and then listen at the front of the car to see if it comes on or not - fan 1 is not very noisy so you need to be close to the grill to hear it .
Little bit more tricky to get fan 2 to come on (at 213)

With the ignition off -

Open the front fusebox and find Cooling Fan Relay #1
it's in the middle
stay away from Relays #2 + #3

Pull relay 1 out and jumper together the two large terminals
the little ones are signal, it won't hurt anything, but they are not the ones.

Both fans should run on slow speed.
if one of them is burned out, neither will run
if one of them is jammed, only the free one will run

To test each fan you would need to open each connector at the motor and give it 12 volts and a ground.

Good luck,

S

ok i will try the jumper technique that stealth suggested. but just out of curiosity what temps should i be seeing at idle after sitting for a while? normal and max/ whats considered overheating?

any sustained idle will bring temps to the point of bringing on the first stage fans - 209f

anything over 215 would be of concern but some people have seen 230+ without it causing a failure ..... 230 is about the point the stock guage moves off its 'normal ' position .

so then i shouldnt be worried about seeing 209F??? that seems pretty high to me...my 400whp rx7 hasnt seen 200F even when beating the hell out of it on the track in 90 degree ambient temps..im afraid if my rx8 sees 209 when its 20F outside whats it going to be when its 90F out this summer?

before you do anything see if you can spin the fans by hand. if not look for what is keeping it from turning.

beers :beer:

well i just replaced the rad with the ron davis rad and i cant remember if i spun them by hand or not..however i do remember there was that infamous rubber grommet in the fan shroud area but it wasn't jamming the fan up, i guess it may have at sometime..

Thanks for the info. I keep meaning to install a switch so I can test/exercise the fans whenever I check the oil.

Fan or relay 2004
 

Okay, I've read 70 different post on the cooling fan issue w/o finding a solution...
I have checked to fuse - its good.
I have puller the relay #1 used a jumper and.... no fans...?
when i place an ohm meter across the fuse and relay terminals it show an open circuit..?

now what..? I think the answer going to be the fans. can someone tell me the best way to get to the fans and maybe pull em???

Also, what about using aftermarket fans..? it is safe? I've read a few posts and someone said something about the ECU not working with aftermarket fans...? any truth to this?

any and all suggestions are greatly appreciated.

DLANC

I'm not sure about aftermarket fans, but whichever you decide to replace them with, the radiator has to come out before you get to the fans. it may not be necessary, however I removed the battery, air box, computer and radiator to get them out. Granted I was changing the radiator any way. It's not hard, just a lot of stuff to take off.

A fan is a fan basically...the ECU will trigger the relay to turn it on...and as long as the load isn't a lot different than stock it will be OK

Easiest thing though is to get a used OEM fan and swap it in...saves you a lot of headaches...and the OEM fans work perfectly fine

Follow up
 

Now I am confused. On my way home yesterday the temp gage jump up past half way point. I pulled over let it cool down a bit them continued home ( only 4-5 miles). I got out the car at the house and I heard the fan running...? Now I am confused. I think it's time to visit the dealership to find out what is wrong vice burning up my motor.

Doesnt sound like a cooling fan issue.

you do know you should change coolant every 2 yrs or so right?

Follow up
 

I do now, thanks.
But I don't see that as the problem. I attempt to test /jump out the fans and I get nothing.

test the fan directly, pull the fan connector out and jump power to the pins and see if it spins.

So i have done this and both fans spin and work. However, i watched the temp reach 215 and the fans never came on until i shut the car was off and the temp read 218, then i could hear and see only the drivers side fan running. Could there be something wrong with a sensor or whatever is supposed to trigger the fans to be activated?

So you installed your own coolant temp gauge, just to scare yourself?

The car is doing what it is designed to do, including running one fan after shut-off.

No, this is off of the ECU (via scan tool) and a gauge i installed, both read the same consistently. Its 60 degree weather out and reaching 220 at a rapid pace during idle, i shut the car off before it goes past 220. During driving the ecu reads 180-195 which i believe is normal. With a mishimoto rad, new hoses, and a new water pump, this cant be normal. The car temp keeps climbing. The fans don't come on at 213 like said above. I've only gotten one to come after it has overheated. Could there be something wrong with a sensor or something else thats supposed to trigger the ECU to turn the fans on? I know those temps are not normal

You just stated that the ecu gives the same reading as your aftermarket gauge so nothing wrong with the sensor, could be something wrong with the relay or related circuitry.
The ecu should ground one side of the relay coil, other side should have constant +12v. If the fans are still functional you should track down a wiring diagram and start checking out the rest of the circuit. Its a fairly simple system.

Do you need the wiring diagram?

...or this DIY that also explains normal fan operation.

DIY fan switches.

If it doesn’t come on a fan or relay is more likely to be bad or possibly a wiring issue. Unlikely that the ECU isn’t sending a signal, but probably the last thing to look for. You can pull a relay out and jumper across the terminals there to see if it runs or not. You need to study the diagram and see the electrical power flow for the various settings. On some if them it flows through more than one relay. Thought I posted electrical flow diagrams for the S1 fan modes on here somewhere 5 or so years ago.

How do you jump power to the fan connectors and relays safely? Or at least test them since the fans only turn on at a certain temperature?

you simply jump a wire from the ground side of the relay power control tab to the chassis. The relay always has power applied to it, but the pcm controls the ground side; off is not grounded, on is grounded.

So take a long enough piece of 16 - 20 Ga stranded wiring, strip 1” of the insulation covering off both ends, remove the relay, put the one bare end of the wire into the relay power side grounding connector tab and reinsert the relay so that it traps the wire in place, and then when you take the other end of the wire and touch it to a suitable grounding point on the chassis.

Which it then bypasses the pcm to turn the relay on if it’s functioning properly. On an S1 RX8 it’s the two relay wiring points in the bottom of this diagram that say “TO PCM”. Which if you understand wiring diagrams it shows the ground for the Relays #2 and #3 being tied together. So you can grab the grounding point on either one to check that part.


https://cimg2.ibsrv.net/gimg/www.rx8...814178602c.png


fwiw, you can bypass the pcm control for both fans with an external controller this way as well.

best wishes
.