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Hi All,

I'm sure this has been asked before, but I couldn't find it. Yesterday, I was driving around with the windows open since it wasn't blisteringly hot out, and the climate control was set to 'fan only.'

I'm 100% positive that cold air was coming from the vents, although the A/C wasn't on according to the car (see below)
photo.jpg

Any ideas why? I'd rather not waste the cold air... Note that the a/c hadn't been used in a while, so this was not residual cooling.
 

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Short answer: It's normal.

I did a search on Google for cold air fan only site:gm-volt.com

One of a host of results: http://gm-volt.com/forum/showthread.php?7998-When-is-FAN-ONLY-not

One example post in there:
Page 8-4 of the owners manual states:

"When in Fan Only mode, the air conditioning system may turn on automatically if the high voltage battery is being cooled. The climate control system could blow cold air."
Hope this helps!
 

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As ClarksonCote wrote, this is normal when the battery TMS kicks on. It will consume battery power even though the HVAC is OFF, but it's part of the system used to protect the battery.
 

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Discussion Starter #4
Gotcha - thanks for the answers and the reference to the other thread. I knew it had to be there, but it's always tough trying to find the right key words to search for. BTW, I guess my only real concern was that the "A/C" status indicator was off while cold air was blowing. I understand that the TMS probably turned the compressor on to cool the batteries, but would have expected the indicator on the dash to admit that. I guess it was off because the cabin a/c wasn't on, even though the compressor was, indeed, on.

BTW, I hit 42 miles of range on a full charge today! woohoo!
 

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Yep, no matter how much the driver is willing to "suffer" with summer heat, the Volt will not allow the battery to suffer. Just another example of a very well engineered car.
 

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Hi All,

I'm sure this has been asked before, but I couldn't find it. Yesterday, I was driving around with the windows open since it wasn't blisteringly hot out, and the climate control was set to 'fan only.'

I'm 100% positive that cold air was coming from the vents, although the A/C wasn't on according to the car (see below)
View attachment 7101

Any ideas why? I'd rather not waste the cold air... Note that the a/c hadn't been used in a while, so this was not residual cooling.
I never liked the A/C in the cabin while running fan mode only. No reason for it that I can figure out. Wish GM folks here might be able to explain the need to cool the cabin along with cooling the HV battery.
 

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I never liked the A/C in the cabin while running fan mode only. No reason for it that I can figure out. Wish GM folks here might be able to explain the need to cool the cabin along with cooling the HV battery.
From other threads, my impression is that the same cooling system is used both for climate control and battery cooling, so cooling the battery also results in the ability to get cold air from the vents. (I am not sure if that means there must be cold air from the vents, or if there's a choice and it's just the auto climate control deciding to take the cool air...)

[edit] Ah, found a detailed explanation: http://gm-volt.com/2010/12/09/the-chevrolet-volt-coolingheating-systems-explained/
 

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They will fix it in the ELR and Volt 2.0
 

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I never liked the A/C in the cabin while running fan mode only. No reason for it that I can figure out. Wish GM folks here might be able to explain the need to cool the cabin along with cooling the HV battery.
The thread linked above explains it pretty well I think. But I'll try to clarify.

When the battery pack requires "active" cooling, the A/C system is necessary so the electric compressor runs to flow refirgernat through the chiller. Since the A/C refirgerant system and battery coolant "chiller" are in parallel with the interior HVAC system, there is no way to prevent flowing refrigerant through the interior evaporator as well.
Then since ALL interior air flow always passes through the evaporator (even when the A/C is off) whenever the evaporator is actively flowing refrigerant (it has it's own TXV to control flow & flooding) it will then be by default removing/transporting heat from the interior airflow.
So it is merely an artifact of the way the HVAC and battery cooling sytems are designed.

A simple and elegant solution really.
Fortuantely if the battery pack requires cooling then typically so too does the interior so it really isnt that intrusive since the A/C has to be on anyways.
My advice is just adjust the temp setting to your desired comfort level and enjoy
WOT
 

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When the battery pack requires "active" cooling, the A/C system is necessary so the electric compressor runs to flow refirgernat through the chiller. Since the A/C refirgerant system and battery coolant "chiller" are in parallel with the interior HVAC system, there is no way to prevent flowing refrigerant through the interior evaporator as well.

My advice is just adjust the temp setting to your desired comfort level and enjoy
WOT
Turn off the fan and the A/C never comes on in the cabin. I assume if I can turn it off, so can GM.
 

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Turn off the fan and the A/C never comes on in the cabin. I assume if I can turn it off, so can GM.
There is absolutely no way to prevent the A/C evaporator in the cabin from becoming active when the battery thermal managment system (TMS) is actively attempting to cool the battery coolant. Shutting off the fan merely stops the airflow preventing the heat exchange, but the refirgeration system is still operational.
HTH
WOT
 

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There is absolutely no way to prevent the A/C evaporator in the cabin from becoming active when the battery thermal managment system (TMS) is actively attempting to cool the battery coolant. Shutting off the fan merely stops the airflow preventing the heat exchange, but the refirgeration system is still operational.
HTH
WOT
I am tracking, would love to know a way to stop the A/C from entering the cabin. It can cool the HV battery all it wants to, the cabin, I don't need it ever.
 

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Since there is no way to "split" the two systems, I would suggest closing the AC vents in the cabin if the cool air bothers you that much.

But having lived with my Volt for 5+ months starting out in Spring (mild temps) surviving the brutal St Louis summer (19 straight days of triple digit temps) and now an early fall (it was 52 degrees when I left the house this morning) the only time the TMS has engaged has been when it's HOT as HELL outside, so any cool air coming out of the vents was much appreciated and needed. I haven't noticed it running in the cool spring/fall temps.
 
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