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Discussion Starter · #1 ·
I have a '16 Volt. When I press the Defrost button, air is directed to the windshield and it works fine. The problem is turning off the defrost feature. When I press the Defrost button again, nothing happens: the light on the button remains lit, and air continues to be directed to the windshield. The only way to turn off defrost is to press "Auto" - which changes all the manual settings I like (venting, heated seats, direction of airflow).

I asked the dealer to look at this, and they said that "GM tech" told them this is normal behavior. I am dubious. How does defrost work on your Volt?

(Note the Max Defrost behaves as expected - I can turn it on AND turn it off just by pushing the Max Defrost button. Turning it off returns all the vent, airflow, etc settings to what they were before I turned it on. All the more reason why I'm surprised that regular defrost works differently.)
 

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I think there is something wrong. Not that I use the defrost buttons much out here in So Cal, but the Defrost and Max Defrost work the same on my Volt - one push turns each one on and another push turns each one off. I just tried it!
 

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The choice between windshield panels or floor is a "mode" and therefore not toggled on or off. You have these or you have auto so what you are seeing is normal behavior. See page 160 of the manual.
 

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The choice between windshield panels or floor is a "mode" and therefore not toggled on or off. You have these or you have auto so what you are seeing is normal behavior. See page 160 of the manual.
This. You'll notice that when you also press one of the other zone buttons (dash or legs) you'll be able to "toggle" the defrost off. Bottom line is that unless you're in "Auto" you have to always have at least one zone active.
 

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while I had high hopes for the addition of climate control "buttons" in the gen 2, their behavior is illogical on many counts. Not saying I would want the Gen 1 system back, but I am often punching an odd "combination" of codes to get desired settings. It likes to switch off certain things when you switch on other things, etc. This is especially true with trying to make adjustments when the recirc is on. I have not tested this defrost issue, but I wouldn't be surprised if its illogical behavior is "normal." I'll try this out next time in the car and report back.
 

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I have a '16 Volt. When I press the Defrost button, air is directed to the windshield and it works fine. The problem is turning off the defrost feature. When I press the Defrost button again, nothing happens: the light on the button remains lit, and air continues to be directed to the windshield. The only way to turn off defrost is to press "Auto" - which changes all the manual settings I like (venting, heated seats, direction of airflow).

I asked the dealer to look at this, and they said that "GM tech" told them this is normal behavior. I am dubious. How does defrost work on your Volt?

(Note the Max Defrost behaves as expected - I can turn it on AND turn it off just by pushing the Max Defrost button. Turning it off returns all the vent, airflow, etc settings to what they were before I turned it on. All the more reason why I'm surprised that regular defrost works differently.)
The defrost button in the center section is just the air flow control selecting windshield, floor, face, or Auto. It is not 'defrost', it is just the selector for choosing which vent to use. Pick one.
 

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Isn't the original poster referring to the buttons shown below circled in red? At the moment in So Cal we could use a de-smoke-and-ash button!
 

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while I had high hopes for the addition of climate control "buttons" in the gen 2, their behavior is illogical on many counts. Not saying I would want the Gen 1 system back, but I am often punching an odd "combination" of codes to get desired settings.
And people look at me funny when I tell 'em I just set it full auto and leave it alone. :D That's why. I don't have to remember how it works because it just does. Maybe not perfectly, but comfortably and I can see well enough, so... why not?
 

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Discussion Starter · #9 ·
The choice between windshield panels or floor is a "mode" and therefore not toggled on or off. You have these or you have auto so what you are seeing is normal behavior. See page 160 of the manual.
Aha, thanks for this. I never set use the manual airflow selection buttons, so I didn't realize that it works this way. And of course, it works differently for Max Defrost.

So I have a reasonable solution: I just direct the airflow to face or feet, then I can turn off the defogger. I'm reasonably happy with this, but still don't see why Defrost can't just work like Max Defrost. It's much more intuitive.

And people look at me funny when I tell 'em I just set it full auto and leave it alone. :D That's why. I don't have to remember how it works because it just does. Maybe not perfectly, but comfortably and I can see well enough, so... why not?
If you have autodefog on, then the Auto setting might work fine. But I can't stand autodefog because it sometimes turns on the a/c when the windshield isn't foggy.

Isn't the original poster referring to the buttons shown below circled in red? At the moment in So Cal we could use a de-smoke-and-ash button!
Yes, those buttons. I hear GM is working on a de-ash button for its next generation of cars geared for the late anthropocene.
 

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Aha, thanks for this. I never set use the manual airflow selection buttons, so I didn't realize that it works this way. And of course, it works differently for Max Defrost.

So I have a reasonable solution: I just direct the airflow to face or feet, then I can turn off the defogger. I'm reasonably happy with this, but still don't see why Defrost can't just work like Max Defrost. It's much more intuitive.
I think you still may be confused. There is NO Defrost and Max Defrost. There is ONLY Max Defrost & Auto Defog. The other button is Windshield Vent. The Auto Defog is set in the center screen setup menus.
 

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... At the moment in So Cal we could use a de-smoke-and-ash button!
Good thing the car comes with a cabin filter. Maybe not at the level of "bioweapon defense mode", but better than nothing. :)
 

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Discussion Starter · #12 ·
I think you still may be confused. There is NO Defrost and Max Defrost. There is ONLY Max Defrost & Auto Defog. The other button is Windshield Vent. The Auto Defog is set in the center screen setup menus.
I know what auto defog is. The rest is a question of terminology. I've heard the button and its functions referred to as Defrost and Defog, but this is the first time I've heard Windshield Vent.
 

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If you have autodefog on, then the Auto setting might work fine. But I can't stand autodefog because it sometimes turns on the a/c when the windshield isn't foggy.
Yeah, when the windshield is about to get foggy instead of waiting until it is. I see that as a good thing.
 

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I know what auto defog is. The rest is a question of terminology. I've heard the button and its functions referred to as Defrost and Defog, but this is the first time I've heard Windshield Vent.
You heard people use it wrongly then. The stuff in the little center ring is purely directional: dash vent, footwell vent, windshield vent. No humidity control involved save whatever incidentally happens due to temperature differences between inside and outside air, and if you turn on recirculation, you lose most of that, too.
 

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I know what auto defog is. The rest is a question of terminology. I've heard the button and its functions referred to as Defrost and Defog, but this is the first time I've heard Windshield Vent.
Just look at the way the controls are laid out, it sorta makes sense. The buttons in the center circled by the chrome trim are all air flow controls. The buttons around the outside are all mode controls.
 

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Discussion Starter · #16 ·
Hm, yeah, that does make sense. However, that logic conflicts with an equally obvious logic, which is what my brain apparently was using until y'all pointed it out to me. Specifically, the defrost symbol ...



...appears on two buttons. So it makes logical sense to conclude that they should work similarly.

But whatever. While I think the controls are counterintuitive, I can live with them now that I know how to turn off "windshield vent" without having to re-set all my other climate settings.
 

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I think you still may be confused. There is NO Defrost and Max Defrost. There is ONLY Max Defrost & Auto Defog. The other button is Windshield Vent. The Auto Defog is set in the center screen setup menus.
Except that it's not that simple. I agree that's what it seems like it should be, but if you set your DIC to show power use and just sit in your driveway with MAX and Eco off, you'll see that if the windshield button is the only one of the three active (all air to the windshield), then you can be using as much as 8kW. With MAX and Eco off and auto-defrost set off, the car should not be using any juice to heat the cabin. If you wait a minute you can feel the heated air. Then, just push the dashboard (face) vent button so there are two places air is going and watch the power drop to the .5kW that the car always uses when it's on and the air will get cooler again.

So GM decided that if you put all the air on the windshield you must want to use power to heat it, even though there are three other buttons available to explicitly do that (Max Defrost, MAX air, and Eco are all supposed to use power). There is no way to run air just at the windshield without using up energy unless you turn down the thermostat (that actually works, but not so far as to run the A/C, good luck finding the sweet spot) or add dashboard air and reach over and close all the dashboard vents. But if you forget and leave the thermostat way down you may not get pre-conditioning to warm the car much.

I tried to tell the service advisor about this and got nowhere (that's defrost, yeah).
 

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Wow! Now I really am thoroughly confused regarding the system. (and I thought I already had it figured out :).....
 

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I just read the section in the owner's manual again covering the climate control. I think either the system is overly complex or the manual is poorly written....or yes, maybe I am just not smart enough to get it.
I think I will just try AUTO for awhile and see how that goes.
 

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Discussion Starter · #20 ·
Except that it's not that simple. I agree that's what it seems like it should be, but if you set your DIC to show power use and just sit in your driveway with MAX and Eco off, you'll see that if the windshield button is the only one of the three active (all air to the windshield), then you can be using as much as 8kW. With MAX and Eco off and auto-defrost set off, the car should not be using any juice to heat the cabin. If you wait a minute you can feel the heated air. Then, just push the dashboard (face) vent button so there are two places air is going and watch the power drop to the .5kW that the car always uses when it's on and the air will get cooler again.

So GM decided that if you put all the air on the windshield you must want to use power to heat it, even though there are three other buttons available to explicitly do that (Max Defrost, MAX air, and Eco are all supposed to use power). There is no way to run air just at the windshield without using up energy unless you turn down the thermostat (that actually works, but not so far as to run the A/C, good luck finding the sweet spot) or add dashboard air and reach over and close all the dashboard vents. But if you forget and leave the thermostat way down you may not get pre-conditioning to warm the car much.

I tried to tell the service advisor about this and got nowhere (that's defrost, yeah).
I just noticed this today as well, now that I've started playing with the venting buttons rather than leaving in on Auto. It's just counterintuitive and stupid in so many ways. What's remarkable is that it's taken me 2 years to figure out how the climate controls work, and I'm still not convinced I 100% understand them.

As for the dealer - well, they are there to fix problems with the car, and they are (probably) correct that your car is functioning as designed. That's exactly what they told me when I complained to them about how the defrost button works (see the first post in this thread). Since it seems that they are correct (so far, all reports here indicate that my defrost button functions like everyone else's), I can't really expect them to do anything about it.
 
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