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2015 Silverado fresh air vent mode incoming air is warmer than ambient

12413

By 12413
in Troubleshooting & Recalls

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12413 Enthusiast

12413

Posted
Posted

On fresh air vent mode I noticed that with the temperature control set to it's coldest point, air coming in through the vents is noticeably warmer than ambient. Any suggestions, I'd rather not run a/c when God has blessed me with the most comfortable natural air?

newdude Senior Enthusiast

newdude

Posted
Posted (edited)

Its pulling fresh air but also ambient engine heat as well. That's why its warmer than ambient.

 

Put the windows down instead.

Edited by 15HDriver
  • Like 1
12413 Enthusiast

12413

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  • Author
Posted (edited)

So it's engine heat. Crappy design if you ask me. Regarding windows: Noise man - nothing is sacred anymore.

 

Thanks for the replies.

Edited by 12413
Supreme Pizza Senior Enthusiast

Supreme Pizza

Posted
Posted (edited)

It may or may not be heat from the engine. The air intake for the vents is generally just in front of the windshield at the base of the hood. The engine heat is generally expelled under the engine. Although its possible that the heat may be radiating up over the fenders and into the air intake for the vents, even a slight breeze would prevent this. It may be possible that your heater controls are not adjusted properly. Here is a way that you could test it:

 

Buy two probe type thermometers. Make sure they are both calibrated the same. Exact temp doesn't matter, as long as they both read the same temp. Stick one probe type thermometer in the main dash vent. Stick the other probe on top of the passenger side headrest, without covering the probe tip. Point the vents away from the passenger seat. Warm the rig up, and let it idle in the driveway, with the vent set to "fresh air intake", no A/C and the setting on the lowest temp option. Wait 30 seconds and compare temp gauges. Now drive the vehicle at freeway speeds, and check the temps again.

 

If the vent temp is only higher than the seat temp at idle, then you are pulling in engine heat.

If the vent temp is higher at highway speed as well, then you need to have the temperature controls adjusted.

 

Doing this test on a cloudy or rainy day is recommended. The sun could heat up the hood, or passenger compartment and throw off the results.

 

 

P.S.

 

I'm making this up as I go, so it may not be a perfect formula.

 

Any HVAC experts out there that can chime in? Am I on the right track with the diagnostic procedure?

 

 

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Edited by starman8tdc
Spurshot Senior Enthusiast

Spurshot

Posted
Posted (edited)

Mine does it too. I think it's blend door not fully closing off the heater core air. The hood has a cowl seal to keep the engine compartment air from going out and into the cowl inlet for the HVAC. My 08 was much cooler on the vent setting. The cowl inlet design hasn't changed since at least as far back as my 79 El Camino.

 

I would put a thermometer in the cowl inlet screen and one at the interior HVAC vent. If the vent air is significantly higher temperature than the inlet air, the heater core is heating it in the HVAC system. I'd guess mine is close to 10 degrees delta.

Edited by spurshot
12413 Enthusiast

12413

Posted
  • Author
Posted

The mixing valve was my first guess. Does it have a means for adjusting its position, maybe a threaded rod of sorts?

  • Like 1
emeryz28 Enthusiast

emeryz28

Posted
Posted

lets get serious, the dashboard and fans and aircon routing are all inches away from a boiling hot v8. It's going to be warmer than ambient and it is not a design flaw, it just makes sense.

 

I have found with the back slider open and the windows open to the correct amount, you can awesome circulation and minimal noise

  • Like 1
12413 Enthusiast

12413

Posted
  • Author
Posted

Fair enough. My 70 Nova didn't have hot engine air mixed in with the vents, nor did my 68 Camaro. It was a good thing they didn't because neither had ac. Unless of course the time that has past has erased actuality from my memory.

 

I like the truck, though I do wish I had a 2500.

12413 Enthusiast

12413

Posted
  • Author
Posted (edited)

It's okay. Ill live with it.

 

No v8

No rear slider

I don't live in Gods country, as a consequence I am forced to hear everyone elses noise. And Believe me,

there's a whole load of it in every direction here. It's an abomination to my senses!

 

I'm sure when that first reciprocating engine coughed into existence it was sweet music. The same goes for Edison's WAX CYLINDER. Ever since then we've been aping on and on. It's mind numbing to think of the degree to which our reproductive capabilities both can and will go. Please excuse my attitude, I must be aging too fast.

 

lets get serious, the dashboard and fans and aircon routing are all inches away from a boiling hot v8. It's going to be warmer than ambient and it is not a design flaw, it just makes sense.

 

I have found with the back slider open and the windows open to the correct amount, you can awesome circulation and minimal noise

Edited by 12413
glendon66 Enthusiast

glendon66

Posted
Posted

On fresh air vent mode I noticed that with the temperature control set to it's coldest point, air coming in through the vents is noticeably warmer than ambient. Any suggestions, I'd rather not run a/c when God has blessed me with the most comfortable natural air?

 

I have to agree that this bothers the heck out of me as well. I assume it's engine heat that I'm mostly getting out of those vents even if I have it set to off or cold (no a/c on.) It's extremely warm and sometimes forces me to turn on the a/c on a day that shouldn't require it. The vents just happen be located in a place where I rest my hands on the wheel and I just feel hot air constantly blowing out of it. I'm living with it but just wanted to let ya know you're not alone in your observation. Cheers!

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