# Coolant Fan "On" Temperature Question



## Cruzator (Dec 31, 2014)

Just curious if anyone knows the temperature at which the cooling fan turns on and back off. Also, when does it reach max speed (my understanding is it is pulse width modulated for variable speed - is that correct?). What about the active grill shutters - what coolant temp do they open? 

Thanks!~


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## obermd (Mar 3, 2012)

The shutters close above 40 or 45 MPH (basically once you hit sixth gear) and remain closed until the car needs the extra air flow. This means they'll close this coming Monday (here in Denver) and stay closed until the temperatures go back up - probably Tuesday evening commute. As for the main cooling fan, it will turn on and off as needed. I'm not even positive the coolant runs through the radiator while the engine is cold.


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## ChevyGuy (Dec 13, 2014)

Keep in mind that the fan is both for engine coolant and the A/C condenser. If the A/C is running, it will probably run more for the A/C than the engine.


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## obermd (Mar 3, 2012)

ChevyGuy said:


> Keep in mind that the fan is both for engine coolant and the A/C condenser. If the A/C is running, it will probably run more for the A/C than the engine.


Excellent point. I've had to run my A/C recently.


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## jblackburn (Apr 14, 2012)

235 on/225 off.

Engine fan runs in low speed for AC and high for engine cooling when requested. Or if the AC high side pressure is too high.


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## Cruzator (Dec 31, 2014)

Thanks, all, for the info. I think I've only heard the fan on once. 235 on is higher than I would like, but I know that's pretty common any more.


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## Cruzator (Dec 31, 2014)

obermd said:


> The shutters close above 40 or 45 MPH (basically once you hit sixth gear) and remain closed until the car needs the extra air flow. This means they'll close this coming Monday (here in Denver) and stay closed until the temperatures go back up - probably Tuesday evening commute. As for the main cooling fan, it will turn on and off as needed. I'm not even positive the coolant runs through the radiator while the engine is cold.


Yes, I hear there another chance of snow coming. I haven't even looked at the shutters yet. Thanks!


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## hondarider552 (Jun 16, 2014)

FWIW, my fan kicks on at 217* reading from my Edge CTS.


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## spacedout (Dec 7, 2010)

hondarider552 said:


> FWIW, my fan kicks on at 217* reading from my Edge CTS.


217-219F is normal operating temps for my stock 2012 1.4T. My fan doesn't come on until 235F mentioned above.


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## jblackburn (Apr 14, 2012)

spacedout said:


> 217-219F is normal operating temps for my stock 2012 1.4T. My fan doesn't come on until 235F mentioned above.


In the summer. Mine runs at 225 in the winter.


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## Cruzator (Dec 31, 2014)

hondarider552 said:


> FWIW, my fan kicks on at 217* reading from my Edge CTS.


\
I put an Ultra Gauge on mine. I haven't been able to watch the fan and temp reading yet, but in stop and go driving (or stopped driving in traffic jam), I've notice it climbs to 219 and then starts dropping, which would be in line with the 217.


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## LiveTrash (May 24, 2015)

I've noticed a fan noise coming from my CTD when I park it and turn it off after a decently long drive during a warm day sometimes, not often though. I guess this is just continuing the cooldown even after the vehicle is off?

Also I saw a post mentioning the shutters that open/close at the lower grill. I had a problem this past winter with snow build-up in the lower grill which eventually turned to solid ice. I unfortunately didn't notice it until quite some time after it built up. I hope this didn't affect the shutters from opening/closing (that is if they even had to during the winter).


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## Robby (Mar 1, 2013)

LiveTrash said:


> I've noticed a fan noise coming from my CTD when I park it and turn it off after a decently long drive during a warm day sometimes, not often though. I guess this is just continuing the cooldown even after the vehicle is off?
> 
> Also I saw a post mentioning the shutters that open/close at the lower grill. I had a problem this past winter with snow build-up in the lower grill which eventually turned to solid ice. I unfortunately didn't notice it until quite some time after it built up. I hope this didn't affect the shutters from opening/closing (that is if they even had to during the winter).


The cooling fan cycles after shutdown for the reason you thought.

The shutters are closed whenever below 45f I think is the target......they are closed on my eco all winter.
If the shutters cannot open when the computer commands it, a check engine light will set.

Rob


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## LiveTrash (May 24, 2015)

Robby said:


> The cooling fan cycles after shutdown for the reason you thought.
> 
> The shutters are closed whenever below 45f I think is the target......they are closed on my eco all winter.
> If the shutters cannot open when the computer commands it, a check engine light will set.
> ...


Never saw any check engine light, so I think it's safe to say my shutters are still working as they should be. Thanks!


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## Cruzator (Dec 31, 2014)

Robby said:


> The cooling fan cycles after shutdown for the reason you thought.
> 
> The shutters are closed whenever below 45f I think is the target......they are closed on my eco all winter.
> If the shutters cannot open when the computer commands it, a check engine light will set.
> ...


I believe the fan continues to run (for a period of time) if shut down during a regeneration cycle to cool down the turbo/DPF (I read that on here somewhere)


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## diesel (Jun 8, 2013)

Cruzator said:


> I believe the fan continues to run (for a period of time) if shut down during a regeneration cycle to cool down the turbo/DPF (I read that on here somewhere)


^^^ this


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