Hello,

My radiator fans were on full blast all the time. I thought the Fan Control Module had gone bad so I replaced it yesterday evening, but this morning when the car was dead cold and it was 60 degrees out, I turned the car on and the radiator fans were going full blast and stayed on 100% of the time.

Is there something else that could be causing this? Faulty temperature sensor?

Thank you

 

It has been my experience that whenever the fans are 'always on' the coolant temperature sensor is the culprit. From the FSM:


Usually when the fan module is shot the fans just don't come on at all.
Are there any codes pending?
I would check the connector at the temperature sensor (remove/replace) and go from there.

 

Thanks a lot!! I guess I wasted my time and money replacing the FCM like an idiot!!!!!

I will check out the coolant temp sensor and plug my obd code reader.

 

Hello again, one more question. Is the coolant temp sensor really on the back of the darn engine close to the firewall?

Thank you

 

Hello,

I plugged my code reader in and it showed the coolant temp at 160 (the car was warm but had been sitting for a while) and then I drove around and it peaked around 182. The fans were going full blast the whole time. What temperature is supposed to trigger the fans?

I also read the codes - no codes were showing.

When I got the new FCM the instructions said a bad fan could draw too much current and blow the FCM. I spun both fans by hand and noticed the passenger side fan did not spin quite as smoothly and freely as the driver side fan. The driver side fan was silent and spun with zero resistance, and the passenger side fan had a little resistance, made a very slight sound, and did not spin as freely.

Could the fan be bad and have blown the second FCM? I'm not sure what else to check or what else it could be.

Thank you for any tips!

 

My fans don't come on till 200 ish. Fully warm I hover around 185 to 195. If i beat her sometimes 200+ fans kick in

 

I have more information, I am getting worried now.

I went out to the car today for the first time, turned on the ignition only, and the fans kicked on full blast. I drove around and they were on the whole time. Then I stopped for an hour. When I came back and turned the car on, the fans stayed off.

I drove home and the fans stayed off the whole time. I plugged in the OBD reader and it said the coolant temp was 220. I sat there idling for awhile looking at all the sensor readings and the coolant temp rose to 278 degrees. Still no fans.

I shut the car off and heard bubbling from the coolant overflow box, vigorous bubbling like it was boiling. At what point would a service engine light come on? That seems pretty darn hot to me. And the fans never came on.

Does this sound like a plausible theory:

One of the fans is going bad so it is drawing too much current
The bad fan blew the second FCM
The FCM failed to turn on the fans when it was supposed to

I am not sure what to do next... should I try to see how much current the fans are pulling? Is it normal for the coolant temp to be 278 degrees and make bubbling boiling sounds?

 

Unless you're looking for engine damage, I would not let temps get that high. Without proper diagnosing it's hard to say what's wrong. Could be any or all of the above. Take it to someone who know what they're doing to get this fixed before you overheat your engine.

 

I am hoping someone here who knows what they are doing can tell me what they would check/test next.

 

so lets get this straight. one day you start your car, out of the blue for no reason whatsoever the radiator fans just blow on high speed. there's no recent collision or modifications? there's no sign of any rodent damage? you didn't do any recent work around the engine bay and perhaps caused an accidental wiring short?

 

Hello, no collision (ever), no modifications of any kind, no rodent damage. Here is the exact sequence of events.

I was driving one evening and noticed the fans were on, which was unusual.
I noticed over the next two weeks that the fans always seemed to be on.
I purchased a new fan control module.
During the installation of the fan control module, I spun both fans by hand and noticed that one of them offered resistance and made noise.
I installed the new FCM and the fans did not turn on for one day.
The next day the fans were on 100% of the time.
A few days later I drove around and noticed the fans were not on at all.
I got home and left the car idling and checked the coolant temperature with my OBD reader and it was very high but the fans were not on.

My conclusion is this:

The fan that is making noise has a bad motor that is drawing too much current. This caused the FCM to go bad.
I replaced the FCM and it also went bad due to the high current draw, but this time it failed in a way that made the fans stay off all the time instead of on all the time.
I will install a new fan assembly (with new FCM) and see if that fixes the problem. The coolant temperature sensor appears to be working correctly.

p.s. I like your location, I also live in commifornia and believe in the constitution and all of the amendments!

 

In my case, both of my fans were not coming at all (whether I had AC on or not)- or barely if that. I, too, replaced the FCM as everything else (ECT, PWM relay, wiring) checked out good. Fans still would not come on at all unless I gave them a spin by hand first. Even then they barely turned.

I ended up replacing both fans (found a complete assembly from a 2017 370Z off eBay for ≈$150.) and haven't had a problem since. Later destructive testing showed both of my fans had a lot of sand contaminating the bearing grease (the joys of living near the beach).

But, NEVER let your engine get that hot again!

 

I've already ordered a new fan assembly, I think that's gonna fix it too. Could my engine already be damaged from getting hot that one time? I drove it for 2 minutes last night and it seemed fine, but I hope I didn't mess up the head.

 

any update on this? I have simular issue, when I have my AC on in stop and go traffic my coolant temp will up. but with my AC off it's fine.

 

Yes, when I installed the new fan assembly that included a new FCM, all the problems went away.

Do your fans turn on? Overheating could be other issues, I'd actually put failing fans lower on the list of possibilities.