AC operational question

[Cobra Jet]

So when using HVAC and selecting "AC" using the SYNC3 screen - the AC system operates perfectly.

When I go to shut it off - going in same way through the screen options, I notice that the "recirculatation" option was automatically turned on... This has happened a few times now - where I have NOT selected that feature when initially turning on and using the AC.

Does the car at some point determine when the recirc feature should be enabled based on interior/exterior temps or fan speed??

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[jasonstang]

If you enable MAX AC, it will turn on re-circulation.

 

[MSMStannyl]

I have a 2015 GT, and therefore Sync 2, but I believe it operates the same way. As was said above, "Max A/C" will automatically go to recirc and turn everything to it's coldest settings. However, I typically just use regular A/C and "Auto" mode. I too have noticed that on occasion, it automatically (at least I assume it's automatic because I didn't turn it on) turns on recirc. I guess that it's based on outside vs inside temps and humidity.

Unfortunately, I haven't paid enough attention (although I will now) but I want to say that I've definitely used the same "Auto" and "A/C" modes with it NOT turning on recirc so it must have to do with the temperatures.

 

[Cobra Jet]

Ok - thanks for responses, but I need to clarify my initial post based on the replies.

I go into the HVAC setting, I select ONLY "AC", and hit the close button to exit the menu. My HVAC system is manually set to "Auto" and I select the temp to be 72*, and fan speed is 2nd to last bar setting for lowest fan speed.

I do not and have not selected:
Dual Climate Control
Max Fan Speed
Recirc
MAX AC

So - just to recap:
AC "on"
Auto Climate Control set to 72
Fan Speed is on 2nd to lowest "bar" speed setting
AC or HVAC controls are not touched after system is initially turned on by me

When I get to my destination and go in through the SYNC menu to turn the AC off, on the available menu AC is selected AND the "recirc" option is now also selected (when it was never previously selected by me and MAX AC was never turned on).

It's as if the car (well, something in the programming logic) is automatically selecting recirculation based on X, Y, Z parameters. I'm surely not selecting it and based on the replies, my manually set parameters wouldn't have activated the setting, right?

I was trying to search on here but must not be hitting any of the correct tags or search words to see if there is an explanation.

??

 

[jasonstang]

It's possible. If its very hot outside, it would turn on re-circulation to prevent evaporator from freezing.

 

[Cobra Jet]

It's possible. If its very hot outside, it would turn on re-circulation to prevent evaporator from freezing.

Hmmm... Interesting, I wonder if that is what is happening?

 

[GTP]

AUTO mode works so well that I rarely take it off, and just let it do its thing.

In fact, the only button that I check is ON is Recirc! I like Recirc to be on by default. Only on a long trip might I turn it off so as to receive fresh air to help me stay awake.

Does anyone experience intermittent outside air temp reading?

 

[MSMStannyl]

I go into the HVAC setting, I select ONLY "AC", and hit the close button to exit the menu. My HVAC system is manually set to "Auto" and I select the temp to be 72*, and fan speed is 2nd to last bar setting for lowest fan speed.

Not sure exactly what you mean by "...manually set to Auto". The Auto setting is just that. You put it in Auto and set your desired cabin temp. The car does the rest (fan speed, which vents its blowing through, etc.). With my Sync 2 system (I assume Sync 3 is the same), I can set Auto with or without A/C being on. However, if you have Auto and A/C turned on, I believe some algorithm is using the inside/outside temp, humidity, etc., sensors to decide when to recirc the air to meet your set temp requirements.

When you have Auto on, I believe your only real options are A/C on/off and temperature selection. In other words, you can't manually set the fan speed, otherwise you'll override the "Auto" setting. Likewise, I don't think you can change which vents are being used or you will also override the "Auto" setting.

I'll have to double check all of that on my way home today but that's been my experience (again, with Sync 2, not Sync 3, although I'm not sure the operation would be any different).

As I said previously, I've noticed the recirc setting automatically turning on (when in "Auto") when it's really hot outside and I'm set to like 67 - 68 cabin temp. Obviously it's more efficient for the system to keep cooling the cooler cabin air then it is to cool the really hot exterior air, especially when you first start a hot car.

 

[jasonstang]

Not sure exactly what you mean by "...manually set to Auto". The Auto setting is just that. You put it in Auto and set your desired cabin temp. The car does the rest (fan speed, which vents its blowing through, etc.). With my Sync 2 system (I assume Sync 3 is the same), I can set Auto with or without A/C being on. However, if you have Auto and A/C turned on, I believe some algorithm is using the inside/outside temp, humidity, etc., sensors to decide when to recirc the air to meet your set temp requirements.

When you have Auto on, I believe your only real options are A/C on/off and temperature selection. In other words, you can't manually set the fan speed, otherwise you'll override the "Auto" setting. Likewise, I don't think you can change which vents are being used or you will also override the "Auto" setting.

I'll have to double check all of that on my way home today but that's been my experience (again, with Sync 2, not Sync 3, although I'm not sure the operation would be any different).

As I said previously, I've noticed the recirc setting automatically turning on (when in "Auto") when it's really hot outside and I'm set to like 67 - 68 cabin temp. Obviously it's more efficient for the system to keep cooling the cooler cabin air then it is to cool the really hot exterior air, especially when you first start a hot car.

On my sync 3, when you hit Auto, it's auto everything meaning fan and vent and AC. You can also take one of these settings to manual mode by manually selecting them for example you can have auto vents but manual fan speed and AC.

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