I tested my radiator fan (passenger side one) outside the car and it runs fine so the fan motor is good but I can't seem to trace the source of why it doesn't go on AT ALL by turning on the a/c or when it reaches temp. It's only the radiator fan that doesn't operate. The Condenser fan runs fine.

I already checked the fuse.
Could it be the relay in the fuse box under the hood?
I'm assuming the fan switch is fine because the other fan operates ok, right?

Is there a way to easily test the cooling fan relay to see if it functions???

Any details will be greatly appreciated!!!

Thanks so much!!!

 

x2... im actually having this same problem... i NEVER notice my rad. fan being on... and its getting hot here. In for answers.

 

Disclaimer - My Lude is a '93 SI, but they are all somewhat similar. (In fact, nearly every car made works exactly the same)

Here are the radiator fan start temps:
194,205 (90,96)
198-208 (92-98)

Stop temp is 4-13 DegF below the start temp.

The ECT sensor is blow where the throttle cable attaches to the throttle body and is screwed into the engine facing toward the front of the car. It will look like a pipe cap with two wires coming out of it. If you measure the resistance of the Engine coolant sensor pin to pin, it should be around 1100 ohms at 90 deg F and around 250 ohms at 190. You can trick the Computer buy putting ordinary resistors across the pins on the harness and the fan should come on. Somewhere around 250 ohms or lower.

Now, at the front of the engine compartment, on the driver's side, right behine the headlights, there are some relays. Mine has a small unit in the rear (A/C compressor diode) and two similar relays in the front. The one farthest forward is the A/C clutch relay and the middle one is the Condenser fan relay.

Finally, be aware that on my car, there is also a separate radiator fan control box under the passenger side feet, just left of the ECU. It is designed very robustly so that even if the ECU fails, the fans will work - and so that a short in a fan will not kill the ecu or damage its outputs.

I hope this helps.

 

Thanks so much for all the info!!!
Those temps should come in handy!
Hopefully the Mugen switch (80) I got does it's job right.

Do you know how to test the cooling fan relay to see if it's functioning properly?

I'm trying to follow the Helm's manual in diagnosing the problem with only (1) fan coming on (radiator/cooling fan) but I'm not sure how to test the relay for problems. I'm also trying to work at the underhood fuse box where the cooling fan relay is located but how can I go about doing the jump wire across it to make that fan turn on or not? If I'm doing it right according to the helm diagram, it doesn't turn on with ignition off.
I'm just hoping it's just the relay for an easy fix eventhough it cost $40 for the relay alone. Just got to make sure it is that before I dish out the $$$.

My condenser fan works fine so there shouldn't be any problems with the relays and such by the driver headlight nor the fan switch on the thermostat housing.

This sucks this should happen right after I did the whole EGR delete with plate. I guess its just my luck these kinds of things happen

 

$15 fan switch on the thermostat housing caused my problem... fixed

 

Was your problem EXACTLY like mine with only (1) fan not working and the other works perfectly???

I thought if the Condenser fan works than the fan switch can't be the culprit, right
At least that's what it seems like from the Helm's manual.

I especially just can't believe the fan switch is the one wrong because it's practically new and it's the expensive Mugen one.

 

the fan switch on your thermostat doesnt have a thing to do with your condenser fan... and i dont have ac.

all i know is it was my fan switch...