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Discussion Starter #1
I've noticed that when I have my Automatic Climate Control (ATC) on, the AC light always stays on, regardless of what temp I have set. So I could have my temp set at 85 degrees and it could be 60 degrees out, and the AC light will stay on

Does this mean the ATC always runs the AC compressor no matter what? I'm just concerned with reduced MPG and slight power loss with the AC always being on.
 

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Replying to Topic 'Automatic Climate Control'

Mine does the same thing. The manual says that you can turn the AC off but that also turns off the automatic climate control. I hope others respond to this, I am interested in what they think:wtf
 

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Reading Topic: Automatic Climate Control

Now days they keep the AC on. If the heat is on they cycle the AC on and off to keep the humidity in check. Even my Miata with full heat on will kick on the AC, if you turn to defrost.
 

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Replying to Topic 'Automatic Climate Control'

QUOTE
Originally posted by LBJay

Even my Miata with full heat on will kick on the AC, if you turn to defrost.[/b]
If you can in your car, turn on your defroster with and without the AC compressor running, and you'll see why they do that...It does annoy me, however, I like the control of being able to turn it off if I should want (which I often do).
 

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Reading Topic: Automatic Climate Control

I was also interested in this, and there was a big discussion about the A/C and auto climate over on the Edmunds forum after I posted a question a couple of weeks ago.

However, I found out something that others might be interested in or want to verify. When reading the manual I saw that it said if you manually change one of the settings (fan, vent mode, A/C, etc.); the other settings remain automatically adjusted. This sounded strange to me, because when you turn off the A/C, the auto light goes out also. But, if you test it out you will see that there actually is a "semi-auto" mode.

Try this: Push the auto button and set a temp, say 75 deg. After the car has run a while and reached a steady state temp(fan speed slowing to the first one or two speeds); push the A/C button. This should turn out both the A/C light and the auto light. If you now turn the temp way up, to sometihing like 85, you will see the fan speed increase and the mode should go to the floor vents. If you then set the temp way low, to 60 deg, the fan will go up and the vents will change to the panel. If you move the temp back to a medium temp, the fan speed goes down and the vents change accordingly.

So, if you want auto control without the A/C on, just press auto, set the temp, and then press the A/C button to turn off the compressor.

Of course, this will only truly be auto climate control if the A/C is not needed to reach the set point. If it can't reach the set temp because the outside air is too hot, the fan just keeps getting faster and the car doesn't get any cooler.

Hope this helps. Try some experiments for yourself.
 

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Reading Topic: Automatic Climate Control

I realize that the AC is used for dehumidifying purposes, and I have no problem with using the AC while raining or to clear windows fog, regardless of what interior temp I have set. But as metioned by Refire, the manual is a bit confusing on this issue.

So redfire, you are confirming my suspicions. Even though the Auto light is off, the Auto mode is still working, correct? i suspected this as well, since I noticed tha same behaviour of the ATC as well. It's sort of like an unmentioned "economy" mode, which most new cars have.

Is it possible that the light just stays on, whether the ATC is using the AC or not? I know the AC light stays off when the defogger is switched on, and the manual states that the defogger utilizes the AC, but doesn't turn the AC light on.

I just wish the system would recognize on it's own when the AC is needed, and turn the AC light on or off accordingly. For example, if the outside temp is 40 degrees, and I set the ATC to 75 degrees inside.... why does the AC light need to be on? I wouldn't need cooling in this situation, and I don't have the defogger activated either. The system should automatically detect this and turn the AC light off to let the driver know it's not utilizing the AC.
 

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Reading Topic: Automatic Climate Control

I dont think you'll lose much in the way of MPG, with the AC on, and maybe I'm old but I remember the bad ole days before automakers started doing this type of thing with the AC and come spring your sweating looking forward to some nice AC and...nothing, ecept maybe a squeel from a frozen bearing. cycling the ac through the winter is a good way to keep everything working properly and if you had a newish car before this (mid to late 90's) the ac was probably on with the heater, there jsut wasnt a light telling you so (ex: my 98 ranger cycled the compressor in every heat setting accept floor, but you wouldnt know it unless you heard it, my 94 gave you control of the ac, but it was much more effective with it on) and besides that I've had cars that have fogged up without warning too, so I think this is a good thing since that hasnt happened to me since oh I would say about 1998.
 

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Reading Topic: Automatic Climate Control

Others have stated in the past that even though the A/C light is on, it is not being used unless necessary. However, this was never definitively answered, and there was some confusion between the A/C being called for by the auto climate control and normal compressor cycling.

I have not personally tested it yet, but I have a suspicion that when the A/C light is on, the compressor is always cycling to maintain proper refrigerant pressure. To test, set the auto control to a high temp for heat and see if the compressor is cycling regularly. I don't think our cars have a moisture sensor, so they probably always run the compressor to dehumidify and avoid the possibility of fogging.

I agree it would be nicer if the car had a little extra logic for determining if A/C or dehumidifying is needed (and show the light accordingly); but this would also require a moisture sensor for completely automatic operation. For now I can live with just cancelling A/C when I don't want it and letting it stay full auto if I need cooling or defogging.
 

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Reading Topic: Automatic Climate Control

The question I posed to MazdaUSA was:

When you turn the ACC on - the green AirCond. light comes on.

Does the compressor run constantly when in ACC mode, potentially affecting mileage, or does it come on and off?

And their answer, verbatim:

"I was advised by my Product Planning contact that if the auto climate
control is on, the compressor will cycle, so it is not turned on
constantly. However, if you just push the A/C button the compressor
will stay on the entire time the button is pushed."

So, the compressor will cycle as necessary to keep from freezing up - but does not run constantly. Your A/C is NOT on all the time - only when needed. Otherwise it's sort of in a stand-by mode.

For the record - I put my car on auto at 75 degrees and have yet to touch it since mid-February.
 

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Reading Topic: Automatic Climate Control

Guess we are going to have refer to the AC as being "Active" and not "On" to keep it clear.
 

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Discussion Starter #11
Reading Topic: Automatic Climate Control

Thanks Ruefus, that seemed to sum it up pretty good.
 
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