On my 03 evo the radiator fan just stopped working. Lucky I looked down at the guage randomly and noticed the car was hot.

I tested the relay and fuse. Both are fine. What I am left with is either I need a radiator fan assembly as the motor may be bad or the fan switch. My questions are

1) where is the radiator fan switch located and how can I test if it is functioning properly.

2) is it possible to hook up direct 12v power to the fan to see if it will come on? This is to test if the motor is fried or not. If it comes on then I am pretty sure it would be the switch.

Any help would be appreciated.

 

Bump?

 

Yeah if you can rig it up separately from the circuit to receive 12v it should run and confirm the fans are not toast. I would also check connection at coolant temp sensor.

 

The coolant temp sensor tells the fan when to turn on and off. Check that and you can also provide 12v from the battery directly to the fan to see if the fan spins.

 

Where is the temp sensor located? How can I test it?

 

What's the small box that is mounted on the back of the fan.

OP, is this box plugged in?

 

the relays are negative switched.
my output on my evo6 ecu died, so i just jumpered it to earth on the ecu.
check to see if you have 12volts going to both sides of the relay (power side and control side).
and go from there.
if you dont have power to either of those, something is wrong with the power system.

 

I dont have the Evo service manual but i believe the sensor is somewhere on the radiator. You can check it with a volt meter.

The small box mounted to the back of the fan is the motor.

 

The coolant temp sensor was next the thermostat housing. Changed that today and still the fan doesn't turn on. At this point it is either the motor or something much worse. I am hoping for the motor.

 

I have an OEM fan assembly sitting around if you determine you need one. LMK

 

this is incorrect.
the ECU tells the Fans when to turn on and off.
The temp sensor if what tells the ECU what the temp is.
The ECU switches the Relay control side to Earth via a transister to activate it.

Did you check to see if the relay has 12v going to the control and power side?
Just pull it out and 2 pins should have 12v, 2 pins should be 0.

 

Ok now the car left me stranded as it wouldn't start. This started after a clutch install. Looking now for grounds to see if they are the problem as I remember reading here somewhere of that being a problem. Grounds to the tranny or something like that causing this type of problem.

 

Ok quick update. There is a ground on the transmission that will prevent a car from starting apparantly. My ground was loose after the clutch install and when I tightened it up, the car fired right up a bunch of times. Hopefully that fixed the no start.

Car not starting after clutch.<--That was just for people doing a search to pull up the post as a possible solution for their problem. Something for the community.

Now to let the car cool down to replace the thermostat. I am thinking a stuck thermostat could keep the fan from turning on. I remember reading that on here somewhere. I do know that the lower readiator hose never gets hot which is a definate problem. Well wish me luck.

 

I had the same thing hapen to me and it was nothing but a ground. That will make your fan stop working. Mine was a ground of the Battery... Gay but it fixed it imediately and the fan came back on!

Mikey

 

Im having the same exact problem with my 2003 lancer evolution GSR. The engine fan stopped working and as a result, my stock radiator cracked, ive since replaced it with a megan racing aluminum radiator and the backup radiator fan isnt enough without the engine fan working. the problem is, mechanics are too busy trying to make money off of you that they kept identifying other "possible problems" when i know its something electrical. One tried to tell me it was my head gasket and cams... (sure okay budyy rigghhht Im not a dumbass) Ummm YEAH thats what i said. I wanna know more about this ground that couldve shorted the fan or how can i wire up the relay to the battery? cant trust mechanincs nowadays so im turning to the forums. Cause even with a mechanic friend, he even said his workers and boss are shady and they need to make money somehow.