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Discussion Starter #1
Does anybody else have this problem (2009 LTZ):

It is winter here and it has been cold. I have the temp and fan both set to auto. Sometimes, when I start the car, the A/C is automatically engaged (the orange light on the snowflake button is on).

This is odd because it's roughly 20 or 30 degrees outside (or possibly 50 degrees in my garage) and I have the temp set for 72, so there should be no reason for the A/C to turn itself on.

I've only had the car for about a month but this has happened maybe 5 or 6 times. Anybody else?
 

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Does anybody else have this problem (2009 LTZ):

It is winter here and it has been cold. I have the temp and fan both set to auto. Sometimes, when I start the car, the A/C is automatically engaged (the orange light on the snowflake button is on).

This is odd because it's roughly 20 or 30 degrees outside (or possibly 50 degrees in my garage) and I have the temp set for 72, so there should be no reason for the A/C to turn itself on.

I've only had the car for about a month but this has happened maybe 5 or 6 times. Anybody else?
Yes, ours does this as well. 09 LTZ

Perhaps this is one of the reasons that I complain about only 20 minutes worth of autostart time and the fact that the car is still cold inside.
 

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On the LTZ when you have the climate controls set to auto, the AC compressor will always be on when the outside temp is above 40 deg.
Page 3-25 in the 08 manual will explain the automatic climate control.
 

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Even if the A/C light is on... The compressor is not actually running. It is still putting out heat. I can't figure out why that light is always defaulted to on whenever you put both dials to auto. Its not a problem though.
 

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Even if the A/C light is on... The compressor is not actually running.
I know it sounds odd, but the manual said the compressor will be on when the outside temp is above 40 deg. F.
 

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Hmm... I thought it shut off the compressor. Your probably right though. You quoted the manual, where as I am just guessing. Lol
I know it still blows out hot air though, so... does it just kinda make the compressor "waste" all its energy?
 

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Hmm... I thought it shut off the compressor. Your probably right though. You quoted the manual, where as I am just guessing. Lol
I know it still blows out hot air though, so... does it just kinda make the compressor "waste" all its energy?
Don't have a clue how it works :D
 

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Lol... Thats my kinda answer.
 

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My '09 LTZ does the same thing, does not make sense to me either when it is 40 degrees and 35% humidity outside and the air conditioning comes on. I am glad I am not the only one annoyed by the apparent waste of energy.
 

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So if it automatically comes on when it's 40+ outside, why has mine been coming on at -20f ??
Sounds like yours is not working properly.
 

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The compressor doesnt just run the AC. It takes out the humidity in the heated air so that it doesnt fog up the inside windows.

If the light is on and you are running the heat its just taking the moisture out of the air. Nothing abnormal about the practice at all.
 

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I haven't figured out exactly what makes the difference for the auto climate control in my 08, but it will occasionally turn on the AC when I first set the system to auto (usually keep the system off) or when starting the car with it turned to auto. I've also noticed that it will turn off the AC light sometimes after running for awhile with it on.

Either way, everything seems to work fine so far as temperature and keeping my windows clear.
 

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It is for humidity control. I don't use the auto climate control anymore. Once I thoroughly cleaned the windows I didn't have anymore fogging issues anyway. Doesn't the A/C suck power and gas whenever it's working?
 

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Hey most newer cars the A/C automatically turns on , on the defrost mode , dont know nothing about the auto climate , but why it turns on is because there are seals in the compressor and the oil eventually seeps through and it starts to leak and wears your seals and ruins your compressor , so with it auto coming on it keeps the oil circulating and from seizing your compressor. Oh and also A/C on with the cold is obviously Air Conditioning , but when you have the heat on and the a/c button it acts as a de-humidifyer.
 

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Discussion Starter #17
Very helpful answers. I guess the answer to my original topic question is that this is not a problem, it's the way it is supposed to work. I will leave the button alone now when it comes on automatically. Thank you all.
 

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We have a similar system in our '05 Honda Pilot which has an auto mode.

By the way, even if the ac is on, it wont blow cold air if you have it set to 72 degrees.
 

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I believe all manufacturers keep the compressor from running when the temp is below 40 degrees. I know that GM does. If they didn't the evaporater would freeze over and you wouldn't get any air out of the HVAC system. To prevent this they usually control the compressor with the low pressure switch in the A/C line. The low side pressure equates to the temp that the evaporater will be running at. When it drops below a point in the 35 to 39 degree range the switch opens and the compressor clutch loses its power. The light on the dash may flicker or even be on solidly on but the compressor isn't running. You can verify this by going outdoors and trying to run the A/C or defroster when its 20 or 30 degrees outside. The compressor will not run at all. The clutch will turn but the compressor shaft will not turn.

Bill
 
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