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Discussion Starter #1
Its a 2017 but assume its the same as many of you. I have the automatic climate control system. My question? When in automatic the system always seems to illuminate the tiny AC indicator and I am forced to press the AC button so the compressor does not run. Even if I raise the temps high the ac still runs. This does not seem correct to me. Especially since I am (non car related) an AC tech myself.

I've read the chapter in the manual and it says nothing about this. Imo the only time the AC compressor should be on is when cooling is desired and/or when you want to assist in defrosting windows. It just doesn't make sense that the AC compressor gets turned on anytime the auto button/function is used. I mean even this morning I tried to use the auto function while cold outside and heat was needed. Sure it still heats but it does so with the AC compressor on. This imo shouldn't be the case. I had to hit the AC button to turn off the indicator and all worked well. But why the AC on always when in auto regardless if you need to heat or cool? Something wrong here? Unless the system is sensing it needs to help defrost may be the only thing I can think of but that being said its not like the system sent air to the defrost vents so I don't think that's the reason. Does anyone else notice this? And/or know why? Does yours do the same?

I mean auto should mean auto and the compressor shouldn't be on unless you need cooling or want to help with defrosting. If one has little knowledge of whats really going on they will place the system in auto and will not even know the AC comp is actrually running all the time even when looking to heat the car. Whats the story with this?
 

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I have a 2016 and have noticed the same thing and wondered about it. Sorry I don't have an answer but it seems to me that it doesn't feel like it's putting a pull on the engine like in summer. I have wondered if it is on at all and that icon is just an indicator of where the A/C button is. Maybe someone will know.
 

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Discussion Starter #3
As I sat in the car at idol I can here the compressor clutch engage and disengage when hitting the AC button. And sure enough in the auto mode it sure seems as though it is on and running. Basically anytime that tiny ac indicator is displayed the compressor is on because if its quiet enough (to listen) you will here the clutch disengage the compressor after you hit the AC button and also the indicator light will then turn off. That tells me it was engaged just by being in auto even though it was looking to heat the cabin.
 

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The only way auto is truly auto is if all systems are online in case cooling is needed. If you hit auto when it was warm out, and then had to hit the a/c button to make it cold you would complain the same just opposite - that you had to turn it on to make it work.

In winter a/c is used with heat to dehumidify the air. No, it doesn't always need to be on but it isn't useless.

Program yourself to hit the a/c button to cancel it out if you don't want it on after turning on auto. It will become second nature very quickly. It's been this way in all 4 or 5 vehicles I've owned with automatic climate control.

The good thing that mazda has allowed is it to remember the no a/c setting after restarting the car if you've left it in auto mode. Some cars do not do this.
 

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Discussion Starter #5
The only way auto is truly auto is if all systems are online in case cooling is needed. If you hit auto when it was warm out, and then had to hit the a/c button to make it cold you would complain the same just opposite - that you had to turn it on to make it work.

In winter a/c is used with heat to dehumidify the air. No, it doesn't always need to be on but it isn't useless.

Program yourself to hit the a/c button to cancel it out if you don't want it on after turning on auto. It will become second nature very quickly. It's been this way in all 4 or 5 vehicles I've owned with automatic climate control.

The good thing that mazda has allowed is it to remember the no a/c setting after restarting the car if you've left it in auto mode. Some cars do not do this.
appreciate the input but disagree about what "true" auto is. True auto would be to put the compressor on only when needed for cooling or if need be to help dehumidify fogged windows if needed. With everything so efficient nowadays and also high tech, the last thing one should be doing is running the ac compressor when not required. Its much better off to only come on when it automatically needs to lower the cabin temp. Then one can also (if they chose) put it on manually to help defrost windows as may be needed. Why lose fuel efficiency having it run when not needed? and why wear the compressor more than needed? Automatic should be just that, it should be "automatic". Should turn on automatically when only a demand for cooling is called for.
 

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Yup, "auto" is not one touch but two - pushing the A/C off after the auto button is occasionally needed.

I always have my cars on defrost/feet mode with the fan on the first setting as I like a constant circulation of air without it right in my face. But occasionally, it blows super cold A/C air while the A/C light is off. I imagine because it's on a defrost setting. I just have to play with the temp setting and/or the A/C button to get it to blow without actual A/C going.
 

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appreciate the input but disagree about what "true" auto is. True auto would be to put the compressor on only when needed for cooling or if need be to help dehumidify fogged windows if needed. With everything so efficient nowadays and also high tech, the last thing one should be doing is running the ac compressor when not required. Its much better off to only come on when it automatically needs to lower the cabin temp. Then one can also (if they chose) put it on manually to help defrost windows as may be needed. Why lose fuel efficiency having it run when not needed? and why wear the compressor more than needed? Automatic should be just that, it should be "automatic". Should turn on automatically when only a demand for cooling is called for.
I'm just saying that from a systems / operations point of view that's how it is and why. There's nothing that can be done to change it, and there could be MUCH worse concerns.

For example: I once had a Nissan truck that if you turned on the defroster (which turns on the a/c) the a/c was then on permanently until the vehicle is restarted. Even hitting the a/c off switch wouldn't turn it off. Now THAT was annoying (I ultimately had to modify the HVAC control unit to stop this, but the consequence was that I had to then manually turn A/C on and off all the time, even for defrost modes).

Once you accept the fact that's how the system works I think you'll be much happier with the way it actually performs. Again, it's not just this car - I've had other Mazda, Volvo, Subaru and Kia vehicles all work the same way. Actually with the other current car (Kia) it doesn't even indicate the A/C is on in auto mode - you can just feel it engaging and disengaging. To cancel it while keep the rest on auto you have to push the a/c button twice (instead of once) to override the system. Once to override it on, then again to override it off.
 

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Before I had a Toyota Prius that worked the way it should. The A/C compressor did not come on when the heater was on and the A/C wasn't needed so it can be done.
 

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Discussion Starter #9
I'm just saying that from a systems / operations point of view that's how it is and why. There's nothing that can be done to change it, and there could be MUCH worse concerns.

For example: I once had a Nissan truck that if you turned on the defroster (which turns on the a/c) the a/c was then on permanently until the vehicle is restarted. Even hitting the a/c off switch wouldn't turn it off. Now THAT was annoying (I ultimately had to modify the HVAC control unit to stop this, but the consequence was that I had to then manually turn A/C on and off all the time, even for defrost modes).

Once you accept the fact that's how the system works I think you'll be much happier with the way it actually performs. Again, it's not just this car - I've had other Mazda, Volvo, Subaru and Kia vehicles all work the same way. Actually with the other current car (Kia) it doesn't even indicate the A/C is on in auto mode - you can just feel it engaging and disengaging. To cancel it while keep the rest on auto you have to push the a/c button twice (instead of once) to override the system. Once to override it on, then again to override it off.
you were correct in your earlier post about the system remembering. If I hit the ac off, the next time I start the car the auto mode will leave it off. That's good to know:)

But to be honest fwiw the situation is imo actually an easy fix. All it takes is a signal to turn the compressor off if/when temp in the car is lower than the temp setpoint. Just the same way it opens a heating coil or changes the air output as well as where the air comes from. For old fashion wiring and tech its just another simple relay circuit and with new computerized tech its just simply another minor program step and electronic output. Its the same really, just the new way.

The problem here (even thought I now understand the operation) is that I bet my house far too many people are driving around with the compressors on all the time and never knowing it simply because they are unaware or simply honestly ignorant to whats really going on. They just put it on auto and let it do its thing but this is not good imo even if it happens in other cars too. Especially nowadays where everything is suppose to be as energy efficient as possible. From sipping least amount of fuel as possible, to being light as possible, to finding happy medium between power output and efficient gearing, heck even now incorporating the recirculation of energy lost in braking back to the engine (or at least attempting to do so). And many now even eliminating spare tires just to save weight for fuel consumption, ridiculous on that one imo but etc, etc, the list goes on...

Point is that allowing the compressor to run all the time (for anyone unaware which will indeed be many) is kind of a ridiculous thing when ya think about it. It goes against everything they are trying to accomplish nowadays with all the high efficient tech. Such an easy fix for something that is very inefficient when viewed that way. Running the compressor requires the use of energy which is power which if fuel consumption. One would think the last thing any maker should do is allow the compressor to run all the time. In fact (going with the modern energy and efficiency logic) if anything at all it should probably always be off unless desired by the operator. I must say I am surprised by this.

I now understand the operation and know what to do but still its surprising this even happens the way it does.
 

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Discussion Starter #10
I'm just saying that from a systems / operations point of view that's how it is and why. There's nothing that can be done to change it, and there could be MUCH worse concerns.

For example: I once had a Nissan truck that if you turned on the defroster (which turns on the a/c) the a/c was then on permanently until the vehicle is restarted. Even hitting the a/c off switch wouldn't turn it off. Now THAT was annoying (I ultimately had to modify the HVAC control unit to stop this, but the consequence was that I had to then manually turn A/C on and off all the time, even for defrost modes).

Once you accept the fact that's how the system works I think you'll be much happier with the way it actually performs. Again, it's not just this car - I've had other Mazda, Volvo, Subaru and Kia vehicles all work the same way. Actually with the other current car (Kia) it doesn't even indicate the A/C is on in auto mode - you can just feel it engaging and disengaging. To cancel it while keep the rest on auto you have to push the a/c button twice (instead of once) to override the system. Once to override it on, then again to override it off.
you were correct in your earlier post about the system remembering. If I hit the ac off, the next time I start the car the auto mode will leave it off. That's good to know:)

But to be honest fwiw the situation is imo actually an easy fix. All it takes is a signal to turn the compressor off if/when temp in the car is lower than the temp setpoint. Just the same way it opens a heating coil or changes the air output as well as where the air comes from. For old fashion wiring and tech its just another simple relay circuit and with new computerized tech its just simply another minor program step and electronic output. Its the same really, just the new way.

The problem here (even thought I now understand the operation) is that I bet my house far too many people are driving around with the compressors on all the time and never knowing it simply because they are unaware or simply honestly ignorant to whats really going on. They just put it on auto and let it do its thing but this is not good imo even if it happens in other cars too. Especially nowadays where everything is suppose to be as energy efficient as possible. From sipping least amount of fuel as possible, to being light as possible, to finding happy medium between power output and efficient gearing, heck even now incorporating the recirculation of energy lost in braking back to the engine (or at least attempting to do so). And many now even eliminating spare tires just to save weight for fuel consumption, ridiculous on that one imo but etc, etc, the list goes on...

Point is that allowing the compressor to run all the time (for anyone unaware which will indeed be many) is kind of a ridiculous thing when ya think about it. It goes against everything they are trying to accomplish nowadays with all the high efficient tech. Such an easy fix for something that is very inefficient when viewed that way. Running the compressor requires the use of energy which is power which if fuel consumption. One would think the last thing any maker should do is allow the compressor to run all the time. In fact (going with the modern energy and efficiency logic) if anything at all it should probably always be off unless desired by the operator. I must say I am surprised by this.

I now understand the operation and know what to do but still its surprising this even happens the way it does when the fix is easy.
 

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I don't disagree with ya, I'm sure the systems will improve over time - I'm sure there must be some technical reason behind the way it works that we don't know about. Bottom line I'm glad we at least figured out something to make it work a bit better for you.
 

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Discussion Starter #12
I just figured something else out here too. While the auto system will indeed remember to leave the ac compressor off the next time you start the car if that's the way you left it when you last shut the car, it will unfortunately go back to putting the compressor on if you shut and then turn the system back on while the car is running.

understanding all this is simple yes, but still imo the whole process is poorly thought out. As said earlier its just simply not efficient. I will guarantee there are plenty people unaware of the whole situation and are driving around with their ac comp on all the time. Imo wasting fuel and ware and tare on the compressor, its clutch, and also fwiw the belt that turns it. While that last two things may be of little significance the first two I feel are. Imo its poor engineering on this one process or simply overlooked by the engineers. Nowadays in this world of high efficiency it should be a no-brainer to have the ac compressor off all the time except when needed or asked for. Just the way I see it.
 

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I didn't like this in our 2016 sGT, but the system "learns" or copies how you last had it, at least on our 2016.

First time, we have to push the AC button to keep it off. Subsequent restarts, the climate control starts off with the AC off.

Ralph
 

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I'm a new member with a 2016 mazda 3 iGrand Touring hatchback. I love my car and the a/c cools great, but I'm not a fan of this HVAC system. I only have the 2.0 engine which is design for economy not power. Why can't I see the temperature setting without the a/c on? And second anytime I change the fan speed the a/c comes on what's up with that? Why should the fan turn on the a/c ? I lost three mpg on a recent trip and could figure out why, it was chilly weather and didn't need a/c. I was averaging 40 mpg last trip but 37 was the best I could do. I get about 44 when I use premium ( not often). Now I'm thinking that the AC compressor was on the entire time. I realize most people want HVAC on all the time, however I mainly drive with off especially in winter but still most like to see the temperature reading. With the a/c off you don't have much control of system at all. It's great when it's on, but not so great when it's off.
 
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