# What HVAC settings will keep Compressor off?



## 17Hatch6MT (Dec 28, 2015)

I have a 2017 LT Hatchback. Manual HVAC. Seems like I can feel the compressor cycling on most if not all HVAC settings (floor, chest level, defrost). What settings or what can I do to disable it? On a cool, dry day I do not need the compressor to defog the windshield, but it runs anyway. Even worse, I've noticed little lurches as if the compressor is cycling, even on settings ('bi-level' for you older GM fans) that don't involve the windshield. Hoping there may be a built-in or easy mod that locks out the compressor in the Cruze.

On my old Sentra there was an unmarked setting that blew air on the windshield without running the compressor. (Theory was, Europeans and Japanese knew how to use it, but it was unmarked in American versions because Americans are too stupid to understand it, lol.) 

With the economy-oriented gearing, it really matters whether the compressor is engaged or not. On the other hand, I haven't really noticed a loss of torque when I need it. Really hard to tell exactly what's happening, though, with the electronically controlled throttle. Maybe the computer is smart enough to shut it off during acceleration at low rpms?

No matter how good the computer is at hiding it, running the compressor when I don't need it is causing fuel economy loss. So I want to know how to ensure it is off.


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## au201 (May 18, 2013)

In the gen 1, and any other car I've had, if it's not on defrost of any sorts, the A/C button isn't pressed, and it's not in automatic mode, the compressor should not be running. In the past, there have been some funky things with having the temperature knob fully turned one way or the other. If you're at full cold, try stepping back a notch. 

And yes, when at full throttle (I'm not sure if it does it at lower throttle positions based on load, I don't think so) the computer will automatically disengage the compressor to give you full power. 


Sent from AutoGuide.com Free App


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## ChevyGuy (Dec 13, 2014)

I believe that in the Gen1, if you select floor vents, the A/C may come on. Regardless of mode, if the outside air temp is really low, it won't come on to protect the A/C.


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## 17Hatch6MT (Dec 28, 2015)

What is the use of the 'A/C' button if it runs no matter what?


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## ChevyGuy (Dec 13, 2014)

A lot of cars will run the A/C when set for defrost. It's to reduce the humidity.

But so far you've only heard from the Gen1 people.


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## 17Hatch6MT (Dec 28, 2015)

Yes, I know that 'Defrost' settings will run the compressor whenever it's on a windshield setting. I'd like the option to blow on the windshield without running the compressor. I can tell if the window is fogging and I want to decide whether to run the compressor to defog. Is that too much to ask? I don't think the car has a humidity sensor, does it? And, especially if I am not asking for windshield air, makes no sense to me to run the compressor unless the A/C button is pressed. I WANT THE OPTION TO DECIDE WHEN TO DEHUMIDIFY. IS THAT TOO MUCH TO ASK, CHEVROLET?!

In years gone by, when cars did not have A/C, we managed somehow. Either by blowing hot air on the windshield, or wiping with a rag. I want the option to blow warm air instead of using the compressor. In the interest of rationality, I'd use the compressor rather than a rag, if warm air isn't enough. That's what the 'A/C' button is for, right?


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## Mikeselky85 (Nov 6, 2016)

I've noticed on mine that it comes on when it's a humid day or in the morning when my windows will fog. Almost every new car will turn the AC on by itself. I'm certified to work on car HVAC and pretty much every car does it now.


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## jblackburn (Apr 14, 2012)

Yes, the manual climate control in the Gen 2 has a humidity sensor and will turn on the compressor in any vent position to keep your windows from fogging up when it's humid. 

I did not find a way to deactivate it, but noticed this on a trip where we were driving through some foggy areas with just fresh air on. Honestly it's pretty helpful - you could see the fog on the windshield starting to appear go away instantly. Sure my auto climate control Cruze does it too. 

As far as AC on with defrost - that's been pretty much standard for the last 20 years or so...


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## Cruzator (Dec 31, 2014)

On my 2014 the only setting the compressor doesn't automatically engage on are bi-level and vent, This is the only car I have ever had that turn on the compressor when set to floor. I have no idea about a 2017.


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## Merc6 (Jun 8, 2013)

On the older cars that will show A/C on defrost, would only show A/C on for windshield only. Windshield and floor combo was not A/C. Cruze gen 1 would still do it. What is your outside temp as chemical a/c is usually deactivated 35*F to about 40*F because it's "Free A/C" outside.


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## 17Hatch6MT (Dec 28, 2015)

It's cold enough now that it shouldn't need to run.
The 'lurch' I am feeling may be the smart charging system activating the alternator during deceleration. I am ok with that!


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## Mikeselky85 (Nov 6, 2016)

Air conditioning is t only used to cool your car down. It creates dry air, and the manufacture uses this to their advantage. Just like clicking the AC button may request for the system to turn on, but the car can still deny your requests for whatever reason it wants. All new cars work this way and there is no definitive way to just make it only work when you want anymore


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## AuditorBill (Jan 6, 2017)

Interesting...I just came on to post why, in the dead of winter, as soon as I turn my '17 LT on and move the fan from 'off' to a speed, the green A/C button light is on. I can guarantee the car wasn't turned off in that position.

I find it a minor annoyance, as I'm sure my wife will continue to drive around with the A/C on in freezing weather, no matter how many times I tell her to push the A/C button to 'off', LOL.


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## ssnscruzeeco2015 (Dec 29, 2014)

The AC will not come on below a certain outside air temperature approximately 0C, it will come on automatically if the vent is set to floor and/or windshield.

I have been able to disable it.... I have installed a switch indicator breaking the clutch control power between the relay and the compressor clutch. could provide a pictures routing details and ,actions required. The switch resides velcroed on the left side of my instrument panel.

What is great is this switch will show white illumination, when the computer demands AC either automatically or manually via the AC button, and if I enable it turns red otherwise it is out.


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## EricSmit (Dec 21, 2016)

Worth noting, I also have a 2017 hatch, and before I tuned it, there were times when I thought the compressor was on but it was actually just the terrible throttle map.


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## EricSmit (Dec 21, 2016)

Also, I assume by your handle that you have a manual. That decel lurch you feel is your injector cutoff. I'm happy to walk you through a few of the different operating features if you'd like, but really it's just abysmal throttle map and a tune will fix that.


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## carbon02 (Feb 25, 2011)

Does the new GEN 2 Cruze have an ability to measure cabin humidity? I have a Nissan that does something similar. It turns on the AC light when the fan is turned on, and the user has to manually turn it off. Something to do with the car trying to determine the ambient humidity in the cabin.

Anyone with GEN 2 Service guide access able to get the HVAC operating description modes?


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## ChevyGuy (Dec 13, 2014)

carbon02 said:


> Does the new GEN 2 Cruze have an ability to measure cabin humidity?


Not sure about the Gen2, but I believe the Gen1 when equipped with automatic climate control does.


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## jblackburn (Apr 14, 2012)

carbon02 said:


> Does the new GEN 2 Cruze have an ability to measure cabin humidity? I have a Nissan that does something similar. It turns on the AC light when the fan is turned on, and the user has to manually turn it off. Something to do with the car trying to determine the ambient humidity in the cabin.
> 
> Anyone with GEN 2 Service guide access able to get the HVAC operating description modes?


Yes, there is a humidity sensor on Gen 2 manual climate control systems. With A/C button turned off, if the humidity in the cabin begins to creep up to the point where windows start to fog up, it will kick on the compressor regardless of what you have it set to.


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