A/C Fan Speed

[jimbowattz]

Anyone know what would cause fan speed to suddenly increase to high speed, or close to high speed, when it's not set to auto on a 2018 Silverado?

 

I have noticed a few times where auto was off and I had speed set to where I wanted, and then the speed increased by itself.

 

Thanks

 

 

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[camcamaro1991]

2 hours ago, jimbowattz said:

 

Anyone know what would cause fan speed to suddenly increase to high speed, or close to high speed, when it's not set to auto on a 2018 Silverado?

 

I have noticed a few times where auto was off and I had speed set to where I wanted, and then the speed increased by itself.

 

Thanks

 

 

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Is it out of warranty?, more than likely its the blower fan voltage regulator, or blower/fan controller, off or 100% is typically a sign its failed.

Edited June 15, 2019 by camcamaro1991

[jimbowattz]

Is it out of warranty?, more than likely its the blower fan voltage regulator, or blower/fan controller, off or 100% is typically a sign its failed.

Not necessary 100%. It just speeds up like it's on auto or compensating for a temp change. I'm at 1500 miles under warranty.

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[camcamaro1991]

4 minutes ago, jimbowattz said:

Not necessary 100%. It just speeds up like it's on auto or compensating for a temp change. I'm at 1500 miles under warranty.

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Are you on your phone/Bluetooth/handsfree/ ? it slows down during calls and will speed up when the call is done.

[jimbowattz]

Are you on your phone/Bluetooth/handsfree/ ? it slows down during calls and will speed up when the call is done.

No, not using Bluetooth when it happens. But that seems like something that would cause what I'm seeing. Are there any other sound related triggers that could cause that?

 

And mine increases, not decreases as if it was trying to quiet it.

 

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[camcamaro1991]

Solar sensor, its the little dome on center in the dash, is it covered? or could be bad as well. 

[jimbowattz]

Solar sensor, its the little dome on center in the dash, is it covered? or could be bad as well. 

Interesting. Not covered with anything. But even if it was, I don't have it on auto. Will have to take note if anything is blocking it next time it happens.

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[camcamaro1991]

2 minutes ago, jimbowattz said:

Interesting. Not covered with anything. But even if it was, I don't have it on auto. Will have to take note if anything is blocking it next time it happens.

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the outside air sensor is also used, in the grille, to assist the A/C with information.

 

 

some more info

 

The climate control system uses the information from these sensors to maintain comfort settings by adjusting the outlet temperature, fan speed, and the air delivery mode. The system may also supply cooler air to the side of the vehicle facing the sun. The recirculation mode will also be used as needed to maintain cool outlet temperatures.
 

Edited June 15, 2019 by camcamaro1991

[jimbowattz]

the outside air sensor is also used, in the grille, to assist the A/C with information.     some more info   The climate control system uses the information from these sensors to maintain comfort settings by adjusting the outlet temperature, fan speed, and the air delivery mode. The system may also supply cooler air to the side of the vehicle facing the sun. The recirculation mode will also be used as needed to maintain cool outlet temperatures.  

 

 

 

 

 

 

 

But isn't that only if it's set to auto? I intentionally take it off auto to set the fan speed that I want. Here is a video showing what's happening. Definitely related to the temperature setting vs actual reading. But if you notice, my auto light isn't on so the speed shouldn't change in my opinion.  

 

  

Additionally, if you watch the screen you'll see that the fan speed indicator doesn't change.

 

 

 

 

 

 

 

 

 

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[camcamaro1991]

41 minutes ago, jimbowattz said:

 

But isn't that only if it's set to auto? I intentionally take it off auto to set the fan speed that I want. Here is a video showing what's happening. Definitely related to the temperature setting vs actual reading. But if you notice, my auto light isn't on so the speed shouldn't change in my opinion.  

 

  

Additionally, if you watch the screen you'll see that the fan speed indicator doesn't change.Sent from my SM-G973U using Tapatalk

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Its really hard to tell there, a lot of noise is coming from you spinning the temp... control knob, the blend doors it will change air flow, no doubt about that that is typical.

 

however maybe 1 of your blend doors is failing, GDS2 is your friend, without it I cant see the doors moving via the diag... tool. outside of doing a feel test of the air bottom, top, windshield, etc...

VCX nano… mans 2nd best friend = tools 

[FIREBLADE74]

My 2017 does this on hot days. The fan speed increases dramatically by itself, not on auto, for about 10-20 second then return to its original setting. 

 

I chalked it up to it trying to cool the cabin down quickly. I occurs shortly after I crank up then pull off.

[Darmichar]

On 6/22/2019 at 5:35 PM, FIREBLADE74 said:

My 2017 does this on hot days. The fan speed increases dramatically by itself, not on auto, for about 10-20 second then return to its original setting. 

 

I chalked it up to it trying to cool the cabin down quickly. I occurs shortly after I crank up then pull off.

This.  I knew I had heard my truck do this before but never really paid attention to it.  I did this weekend.  After the truck sat in the sun in the Costco parking lot, the first 10 minutes or so it apparently put the A/C into recirculate mode and turned the fan up a bit to quickly cool the cab.  About 10 minutes into the trip home, the fan slowed to the setting I had it set to and I could hear the sound change in the dash like it does when I turn on/off the recirculate.  

 

At no point during any of this was my HVAC controls set to automatic.