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L36 cooling fans on as soon as fired up


KingVee

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Well it all starts with a SES light that says the thermostat is at fault in my mechanic's computer, although we all know it isn't the problem because the engine just stays cold all the time.

 

The fans run as soon as I fire up the car, and now I don't seem to have any TCC lockup. He had to disconnect the fan relays/fuses (in that little box thingy), run the car up to operating temperature (or almost) and then reconnect the relays for the car to run like it should - although TCC is seemingly still missing.

 

He's going to look on his end to find why the fans would want to run all the time, but we might have come to a first conclusion that the temperature sensor(s) could be bad.

 

 

I come on here to try to gather information on my own end, because a lot of you guys are gurus and I'm hoping you can help me here. Sure is a lot of things that could be wrong, but maybe there is one or two more common than the others? I don't know...

 

Please and thank you. :)

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Yeah, I'm gonna second Robert. Of course, if your coolant is not getting up to operating temperature, the computer is not going to allow the TCC to lock.

 

I would say...change the thermostat first, and see if that solves the problem. That might as well solve the problem with your fans running all the time too.

 

Also, if you are constantly running your car with the windshield defroster on, this causes the A/C compressor to run, which also will cause the electric fans to run.

 

I know it doesn't make complete sense, but I have seen stranger things happen.

Edited by tornado_735
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x2 on making sure the A/C compressor isnt on because that will cause them to run... Other than that, check the ECT as it sounds like its giving off false readings

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x2 on making sure the A/C compressor isnt on because that will cause them to run... Other than that, check the ECT as it sounds like its giving off false readings

I haven't used the heater in two months...

 

What's the ECT? /noob

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This doesn't have anything to do with the heat. If you use the windshield defroster (say on a morning when your windshield has condensation on it) the A/C compressor will run. This, in turn, causes the radiator fans to run.

 

First things first though, you need to change that thermostat, because a cold engine is an extremely inefficient engine. :showoff:

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This doesn't have anything to do with the heat. If you use the windshield defroster (say on a morning when your windshield has condensation on it) the A/C compressor will run. This, in turn, causes the radiator fans to run.

 

First things first though, you need to change that thermostat, because a cold engine is an extremely inefficient engine. :showoff:

On the digital climate control, the windshield defroster works with the heat. And my windows don't condensate/fog/frost in the morning.

 

I am very doubtful about needing to change the thermostat as of now though, because it seems to work as it should, but I already know about the inefficiency part since it drinks quite a bit. I mean, can a 'stat be bad even though it does open and close?

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I may be wrong, but I seem to recall that if the ECM detects a problem with the TCC circuit, the fans running was one of the symptoms. I'll check my FSM later, but I'm reasonably certain of this.

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I checked, looks like my memory was faulty. :dance: However, I'm sure I've seen this before, there was a DTC, the check engine light was not lit, the fan running was one of the symptoms, and possible wiring issues was the cause. Do you have any codes stored in the ECM? That would be a good place to start in any case... Good luck!

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Could it be just a safety precaution from some sort of heat condition? The computer is now just in safety mode running the fans and the code just needs to be cleared? I won't lie, I do not know the specifics of the ECM one bit.

 

I would make sure the thermostat is still good. It is a cheap insurance policy. Make sure it is not backwards as well.

Edited by oscar_wilde
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My temp gauge is always a hair below the 1/4 mark... The 1/4 mark is 195 degrees... Mine runs at 185-190 usually

In your 03???

 

My gauge says 100 halfway, how can yours be different? Oh wait, did they really convert Fahrenheit and Celsius?!

 

 

As for updates, my car has seemingly been running to operating temperatures and my SES light eventually vanished last night. ALTHOUGH, it has come to my attention that MAYBE the fans do not turn on anymore. If fans don't turn on, shouldn't it throw a code in and light the SES back on? Additionally, could my mechanic have inadvertently blew/broke a relay fuse while taking it out?

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In your 03???

 

My gauge says 100 halfway, how can yours be different? Oh wait, did they really convert Fahrenheit and Celsius?!

 

 

 

Yes, the Canadian cars got a slightly different cluster with C on it instead of F... The US cluster has 210 for the middle hash...

Edited by 88red4cyl
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In your 03???

 

My gauge says 100 halfway, how can yours be different? Oh wait, did they really convert Fahrenheit and Celsius?!

 

 

As for updates, my car has seemingly been running to operating temperatures and my SES light eventually vanished last night. ALTHOUGH, it has come to my attention that MAYBE the fans do not turn on anymore. If fans don't turn on, shouldn't it throw a code in and light the SES back on? Additionally, could my mechanic have inadvertently blew/broke a relay fuse while taking it out?

They shouldnt turn on at normal operating temperatures unless the AC is on...

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They shouldnt turn on at normal operating temperatures unless the AC is on...

Gauge-wise, where should they start? (approximately?)

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Kind of sounds like a t-stat to me. Mine got stuck open(I think, I always get open and closed mismatched) and it caused the fans to stay on at all times.

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if a thermostat was stuck open, the engine would never(or at least take quite some time) get up to temp and the fans would never come on...

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:dunno: My fans were on all the time, therefore never allowing the car to get up to operating temps. Threw the same thermostat code as KingVee....so you tell me...
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if the fans are on, the PCM either thinks or knows that the engine is overheating. if the stat was open, the engine would never build up heat. the Elky was a good example of this(no stat), and the coolant temps were lucky to hit 120*F except when stopped for more than ~3 minutes on a hot summer day. consider that as a stat-open situation. it also had a belt-driven fan...

 

and even if the fans were always on, coolant doesn't really go through the radiator with the stat closed, so technically your fans could run all the time and not make a bit of difference to your coolant temps if the stat was stuck closed...

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Oooh, the debate...

 

Everything seems to have gotten into place by itself. Although I still have no sign of fans turning on, the temperature gauge mostly roams around the first quarter and sometimes close to half if I'm stopped for a while. It seems to flow though, no cooling issues at the exception of the fans since I have no clue.

 

After driving for a while, especially friday when I came back from my cruise to the Ontarian border, the idle gets erratic going up and down and there's some kind of an issing noise with that. No clue what that is, if I give it some gas, it seems to go away. I don't think this problem is in relation with the rest anyway... ONE PROBLEM AT A TIME, PLEASE!

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