2016 silverado 3500 hvac still blows after turning off

DirtyMaxintheMac · July 16, 2016

New owner to gm trucks and wondering if this is normal.

I have the hvac running in my truck to either cool or heat. But when I shut off the power button to it, it will still continue to blow air. Feels like its on the lowest setting still. Maybe something is stuck open?

It will stop blowing air when I come to a stop. But will pick back up again when I speed up. It does this in all setting.

Also it doesnt seem like the recirculation is working correctly as it smells like its taking in outside air still.

I drive past a couple big oil refineries in northern alberta everyday to and from work. So I like to usually cut the air off for a few minutes or put it on recirculation. But its still brings in the stank either off or running with the recirculation.

Thoughts?

newdude · July 16, 2016

Normal. Equalizes cabin pressure. The fan is off however. Been like this since the GMT-800 at least.

Air vents blow warm air on the side windows in cold weather. If Floor, Defog, or Defrost modes are selected, a small amount of air will come from the vents close to the window. If the airflow is shut off using the thumbwheels, warm air will be directed to the other instrument panel vents. This is normal operation.

If the fan is off, outside air will still enter the vehicle, and will be directed based on the position of the mode knob. The temperature can also be adjusted using the temperature knob.

Kin Korn Karn · January 4, 2018

On 7/16/2016 at 12:28 PM, DirtyMaxintheMac said:

Also it doesnt seem like the recirculation is working correctly as it smells like its taking in outside air still.

I drive past a couple big oil refineries in northern alberta everyday to and from work. So I like to usually cut the air off for a few minutes or put it on recirculation. But its still brings in the stank either off or running with the recirculation.

Thoughts?

Folks, thought it was time to get more savvy about my truck and joined today to start with this query.

Recirculating air in cabin: this setting appears to not work. I get all kinds of ambient scents in the cabin when, in all my experience with other vehicles, I shouldn't be when the unit is set to recirculate. Exhaust fumes from trucks in front of me, dead skunks and roadkill, smoke from burning brush. It enters the cabin as if I have the unit set to fresh air. Is this a known issue with our trucks or do I have something that needs to be repaired?

This thread is the only one I pulled up in searching, hence the thread resurrection.

Thanks for any replies.

newdude · January 4, 2018

Recirculation door only closes the fresh air portion up to 90% on these trucks. The door does not 100% block off outside air. This affects all K2 trucks, so 2014-2018 1500, and 2015-2018 HD. It was a production run change back in January 2014 due to excessive dust in the interior with the original programming where the recirc door closed 100% all the way.

AKNick · January 6, 2018

On 1/4/2018 at 12:48 PM, newdude said:

Recirculation door only closes the fresh air portion up to 90% on these trucks. The door does not 100% block off outside air. This affects all K2 trucks, so 2014-2018 1500, and 2015-2018 HD. It was a production run change back in January 2014 due to excessive dust in the interior with the original programming where the recirc door closed 100% all the way.

How does the recirc door closing all the way contribute to MORE dust in the cabin? Genuinely asking as I do not understand why the door being closed somehow creates more dust??

Next question: Sooo...anyone know how to get to the recirc door on these K2 trucks? If it only closes 90%, then I want to close off the last 10%. I'm with OP in that I've never owned a vehicle where recirc DOESN'T block pretty much all outside smells. I'm really getting sick of smelling cig smoke through the vents on my new truck. Other than that though and some small complaints about the seats, I'm pretty pleased with the 2018 2500HD CCLB 4x4 LTZ a few weeks ago!

redwngr · January 6, 2018

Slight positive pressure inside the cab prevents/reduces dust entry thru seals and other imperfectly sealed openings.

AKNick · January 6, 2018

Ah, found it:

Quote

Condition/Concern

Some customers may comment that they have excessive dust intruding into the cabin of their pickup. This concern will be more noticeable when the HVAC is in recirculation mode. When in recirculation mode, the outside air is completely closed off and the HVAC system is recirculating 100% of the cabin air. This will cause very low cabin pressure and may allow dust to enter the cabin at various locations.

GM Engineering has released updated HVAC calibrations which will close the recirculation door 90% when in recirculation mode. This will allow the HVAC system to draw in approximately 10% outside air, thus slightly pressurizing the cabin, making it more difficult for dust to enter the cabin. This is similar to how the previous generation truck's recirculation mode operated.

Note: This new calibration may have a marginal decrease in HVAC cooling and slightly more outside ambient noise being heard in the cabin, while in recirculation mode.

Kin Korn Karn · January 6, 2018

Ah, found it:

Condition/Concern
Some customers may comment that they have excessive dust intruding into the cabin of their pickup. This concern will be more noticeable when the HVAC is in recirculation mode. When in recirculation mode, the outside air is completely closed off and the HVAC system is recirculating 100% of the cabin air. This will cause very low cabin pressure and may allow dust to enter the cabin at various locations.

GM Engineering has released updated HVAC calibrations which will close the recirculation door 90% when in recirculation mode. This will allow the HVAC system to draw in approximately 10% outside air, thus slightly pressurizing the cabin, making it more difficult for dust to enter the cabin. This is similar to how the previous generation truck's recirculation mode operated.
Note: This new calibration may have a marginal decrease in HVAC cooling and slightly more outside ambient noise being heard in the cabin, while in recirculation mode.

Thanks AKNick.

I suppose I would rather have more dust in my truck that I can clean out over a non functioning recirculate mechanism. I would love to know how to override this and have the door close 100%.

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redwngr · January 6, 2018

Charcoal filter?

Maybe somebody makes/sells one. Seems like there might be a market.

Kin Korn Karn · January 7, 2018

Charcoal filter?

Maybe somebody makes/sells one. Seems like there might be a market.

Certainly worth looking into. Good idea!

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AKNick · January 17, 2018

Just to update:

It appears turning the HVAC 100% OFF closes the intake door(s) completely. Sucks to have to turn it off, but I'd rather be too cold for a few moments than have my nostrils assaulted with cig smoke.