Air Conditioning and Auto Mode

[dub mon]

Hi Folks,

I have a 2008 CX-9 GT. Whenever I hit the "Auto" button on my temperature controls, the A/C (Air Conditioning) green light always goes on (illuminates) regardless of the outside temperature - even in the winter (say 2 deg's C).

From reading the manual, there is a little sensor (black numb) on the top of the dash on the driver's side that measures temperature/light(?) and controls the A/C function.

Is my vehicle mal-functioning or does the A/C light always go on when Auto mode is selected? Does it mean that I'm using A/C always in Auto mode or does it mean that it can use A/C in Auto mode if the vehicle so chooses.

Please enlighten me. I find this interface quite confusing.

thx in advance for the help.

 

[CX9 SportOwner]

It just means the compressor is available to come on, if needed. If you change the temp setting enough to need A/C, then it's already set to engage. It's not running the compressor all the time.

It's actually a pretty simple interface. Set the Auto to On, and then just choose a temp.

 

[dub mon]

Thanks CX9 SportOwner. Your explaination makes sense.

Is there anyway to engage the Auto mode but force the A/C not to come on?
I'm looking for an Econ (Economy) mode that has been present on various vehicles
that I've owned.

It just means the compressor is available to come on, if needed. If you change the temp setting enough to need A/C, then it's already set to engage. It's not running the compressor all the time.

It's actually a pretty simple interface. Set the Auto to On, and then just choose a temp.

 

[hamproof]

Thanks CX9 SportOwner. Your explaination makes sense.

Is there anyway to engage the Auto mode but force the A/C not to come on?
I'm looking for an Econ (Economy) mode that has been present on various vehicles
that I've owned.

Might be tough to regulate the temperature then. If outside is 90 and you want 70 inside

Econ mode, you just need to not use AUTO, and keep A/C off.

 

[The-9]

Thanks CX9 SportOwner. Your explaination makes sense.

Is there anyway to engage the Auto mode but force the A/C not to come on?
I'm looking for an Econ (Economy) mode that has been present on various vehicles
that I've owned.

It would no longer be auto if you could do that. Economy mode is simply outside fresh air with no conditioning.

 

[GoFast]

Are you all sure about it not actually running?

Here is a link to a similar discussion about the MS3 so I am not convinced that mazda would make it that much different in the cx-9

http://www.mazdas247.com/forum/showthread.php?t=123735997&highlight=auto+ac

 

[The-9]

I call bull to that poster and their findings of 3mpg increase when not on auto.

The AC compressor WILL run even at cold temps to help condition the air (yes the heated air) if your vehicle to prevent fogging up. Turn you defroster on in any vehicle you want in the winter and when the temp of the heat gets warm enough, the AC will cycle every so often to help remove the moisture form the air.


Put it on auto and be happy. But if you are really worried about the minuscule amount of fuel you will use to run it in the winter or summer for that matter, leave it off of auto.

 

[CX9 SportOwner]

even on a standard HVAC system, the compressor only comes on when the system calls for it to maintain temperature. We've all heard it click, which is the solenoid engaging the pulley wheel on the compressor. Otherwise, it spins freely.

Yes, in defog (the FRONT button), the compressor does come on to dehumidify the air. (one of the best defog systems I've seen on a car)

Even in summer the A/C running has a negligible effect on MPG with this engine. On our gutless 4 cylinder CR-V, that was a different story.

 

[hamproof]

This is the explanation offered by an "expert".

***********************************************
Different supplier has their own logic regarding A/C control.

Generally, aside from engine coolant temperature requirement, the A/C control definitely relies on outside temperature.
When it's cool, the A/C would turn ON occasionally to maintain the Temperature-Setting requested by the driver. If it's very cold (during winter), the A/C will NOT turn ON at all to protect the compressor from seizing (the oil inside the compressor will be too viscous to lubricate the parts).
When it's hot, the A/C would definitely stay ON all the time at "Outside-Air inlet mode". However, if the driver puts on "Recirculation mode", the A/C would cycle when the evaporator gets too cold to prevent freezing.

But of course the engine coolant temperature requirement preceeds the outside air temperature logic. When the engine is too hot, the A/C will cut-off to help cool off the coolant. ***********************************************

 

[ceric]

A/C still has a significant impact on CX9 MPG.
On my daily route on which I usually get 17-18mpg.
Once in a while, I turned off A/C completely, I could see at least 1 mpg gain.
This has been tried several times.
However, I run my A/C on auto.
On a 4-banger, the impact of running A/C is much higher. On my old Integra, turning off A/C was like switching on turbo.....

 

[The-9]

How are you going to see a 1 mpg gain if you *once in a while* turn off the A/C. Do you know how to calculate mileage the proper way or are you looking at the wonderful little readout the Mazda gives especially after you reset it(rofl2)(rofl2)(rofl2)(rofl2)(rofl2)(rofl2)

 

[CX9 SportOwner]

You would have to do this on a dyno, or a controlled track. Run it with for X miles at X speed with A/C on, then again at same speed and miles with it off.

Even a fixed route will yield wildly varying results. Temp, traffic, stops...

 

[vikefan7]

It seems logical to me that running the A/C would impact mileage, are you guys refuting that?

 

[CX9 SportOwner]

No, just the AMOUNT. The stronger the engine, the less the impact.

On my truck, when the compressor kicks on it feels like I touched the brakes. On the car, nothing.

 

[The-9]

it's all relative: Let's say a 4 cylinder that gets 25mpg would lose (using exaggeration) 3mpg with the A/C on. However, 6cyl that gets 22mpg would lose 2mpg with the A/C on and an 8cyl that gets 17mpg would lose 1mpg with the A/C.

With A/C
4 cyl = 22 Mpg
6 cyl = 20 Mpg
8 cyl = 16 Mpg

4cyl still outperforms (mpg)then bigger engines even with the A/C running so why all the hub bub about the A/C (attn)(attn)

 

[CX9 SportOwner]

Exactly

 

[CX9 SportOwner]

If you're that worried about MPG you buy a Yaris, not a CX9

 

[ceric]

How are you going to see a 1 mpg gain if you *once in a while* turn off the A/C. Do you know how to calculate mileage the proper way or are you looking at the wonderful little readout the Mazda gives especially after you reset it(rofl2)(rofl2)(rofl2)(rofl2)(rofl2)(rofl2)

With ScanGaugeII, I can even measure MPG of 100M travel.
ScanGaugeII automatically resets itself in measuring MPG
(CURRENT, TODAY, YESTERDAY, THIS TANK, etc.)
The observation I did was based on multiple early morning commute trips from my home to where I worked, 16 miles one-way. Normally 16-17mpg with A/C set to auto around 70F. Without A/C, I could get 17-18mpg on multiple runs (different days).
That was pretty conclusive in my view.

 

[ceric]

If you're that worried about MPG you buy a Yaris, not a CX9

I was just saying that it matters, not that I really care about 1mpg.
Pumping up tire to 40psi would also give you 1-2mpg if you can live with the hash ride.

 

[CX9 SportOwner]

I know. I was speaking in general terms. Our CR-V got 26 all the time, but I wouldn't go back.