Rear HVAC user tips? 2019 CX-9 Signature

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North of Toronto
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2019 CX-9 Sig
I tried to read manual, but am still unsure.

Pressing REAR button on dash seems to activate AC in rear. So it's useless in winter I believe? But in summer, does that mean the rear AC is activated but front might not be/doesn't need to be?

And pressing AUTO button seems to sync the whole cabin? AC or heat? Thus sync should be displayed on back?

Wife and I tried to figure out but became a button pressing competition.

I have a Canadian bought cx9, if that makes diff.
 

sm1ke

Work In Progress..
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Contributor
:
Canada
:
'18 CX-9 Signature
I tried to read manual, but am still unsure.

Pressing REAR button on dash seems to activate AC in rear. So it's useless in winter I believe? But in summer, does that mean the rear AC is activated but front might not be/doesn't need to be?

And pressing AUTO button seems to sync the whole cabin? AC or heat? Thus sync should be displayed on back?

Wife and I tried to figure out but became a button pressing competition.

I have a Canadian bought cx9, if that makes diff.

I've got a 2018 Canadian spec CX-9. I believe the REAR button on the dash will enable the controls for the 2nd row and will allow A/C and heat air through the 2nd row vents. We use ours year round - my wife rides in the back when we have our daughter in the car, and after dropping her off, we both ride up front so I turn the 2nd row vents off. And I believe you're correct about the AUTO button, for A/C and heat.
 
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2016 CX-9 GT AWD
I believe hitting the Rear button means you control the rear using the front hvac controls. Leaving it disables means the second row control settings take effect.
 
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North of Toronto
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2019 CX-9 Sig
Months later, adding some info here.

We decided to sort of just ignore this until recently. Figured out one thing that was throwing me off, was the REAR button light being on did not give me control of rear HVAC from driver's seat. You'd think light on, means you're synced. Nope. Not in my vehicle anyway.

To ensure I have control, I now press REAR button (light off), then press on again. That syncs the temp and fan power in back with front. Even if after a subsequent ignition the REAR button light is still on, I do not have control until I double press.

Unfortunately, this has a byproduct of resetting the fan direction in rear. Regardless of where it was blowing air before, after this on/off sequence, it defaults to air flow for feet only in rear. And we haven't figured out how to change this from front. The button in back to change and send air toward the faces of rear passengers is within reach from front set, but to find it while driving isn't possible.

At this point I'm glad I can at least sync the temp and amount of air flow, I'm thinking a little sticker/tape on the rear button would allow the driver to then press and adjust fan direction by feel.
 
This is pretty confusing set-up, and I also wish I had a set of eye back there to completely figure out because the user manual is not clear at all on this subject.

If your front HVAC is set to auto, then I think the rear will set to auto during the REAR-button double press. The airflow in the rear in auto is controlled by the temperature. If it is blowing hot air it will blow at the feet. If it is blowing cold air it will blow towards the face of the passenger. That's standard for almost all auto set-up (hot air rises, cold air goes down). So on Auto that logic works in my CX-9, as fall came by my daughter started complaining she wasn't getting "the wind" in her face that she had all summer.

I am not sure the REAR automatically gets out of sync everytime the car restart, but I also noticed that double pressing the REAR button re-syncs the rear (It is as if the rear HVAC doesn't tell the front HVAC that it isn't sync'ed anymore, and the light stays on, which is a pretty dumb oversight if that is the case.)

When in sync I believe the front fan direction control the rear as well (from foot to face vent) in my 2018, but I would have to run some tests first to be sure.
 
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North of Toronto
:
2019 CX-9 Sig
Just took another look at the online manual.

I think it is saying pressing AUTO in front and in back are 2 independent operations, and they don't affect one another. So if I'm alone, and I hit AUTO in front, it reads my desired temp and sets fan power, fan mode (feet,face, etc) and even recirc based on the temp for the front ONLY. Rear AUTO button does the same but for back only. Which I guess is ok except when the passenger is too young to press AUTO.

I wonder then if pressing REAR after AUTO is selected means the car does the choosing of fan power, fan mode etc for both front and rear. Which would be why it is going to feet in back when I press REAR. The dual selection means the car is doing the thinking for HVAC for me for the whole car.

I wouldn't mind this too much, except there is no way heat to feet in a Canadian winter is sufficient for most people. I want the heat to envelope me, not waft thru physics toward the roof from the footwell. The default being feet makes me never want to use the AUTO button.

Question is, if I deselect auto, would it remain deselected at next ignition. And if deselected, and I select REAR, does my front HVAC control for fan mode also then control the back (after all, now there is no override of the system doing the thinking for me)

Geez, I think typing all this is helping me figure out the system, but props to anyone still reading this rambling post.
 
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‘17 CX9 & ‘19 6 GS
Just took another look at the online manual.

I think it is saying pressing AUTO in front and in back are 2 independent operations, and they don't affect one another. So if I'm alone, and I hit AUTO in front, it reads my desired temp and sets fan power, fan mode (feet,face, etc) and even recirc based on the temp for the front ONLY. Rear AUTO button does the same but for back only. Which I guess is ok except when the passenger is too young to press AUTO.

I wonder then if pressing REAR after AUTO is selected means the car does the choosing of fan power, fan mode etc for both front and rear. Which would be why it is going to feet in back when I press REAR. The dual selection means the car is doing the thinking for HVAC for me for the whole car.

I wouldn't mind this too much, except there is no way heat to feet in a Canadian winter is sufficient for most people. I want the heat to envelope me, not waft thru physics toward the roof from the footwell. The default being feet makes me never want to use the AUTO button.

Question is, if I deselect auto, would it remain deselected at next ignition. And if deselected, and I select REAR, does my front HVAC control for fan mode also then control the back (after all, now there is no override of the system doing the thinking for me)

Geez, I think typing all this is helping me figure out the system, but props to anyone still reading this rambling post.

The only way to select and control the air direction in the REAR HVAC is by manually selecting the flow from the rear. You cannot control airflow in the rear from the dash up front. Pressing the REAR button on the dash does nothing other than toggling between on/off. If you press REAR on the dash twice (off then on), it simply engages AUTO SYNC in the REAR HVAC.

It may sound confusing but once you figure it out then it’s easy to understand. I wish there was a way to control the REAR HVAC from up front but that’s the way Mazda designed it. When I’m driving alone and want to change the airflow direction in the REAR say during winter when its not enough just blowing heat to the feet, sitting from driver’s seat & starting from the AUTO sync setting, I have memorized which button from the left to press (airflow direction) then the number of times to press it (for blowing to the face). Not ideal but works nonetheless...
 
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