Automatic Climate Control (New Member - First Question)

GMCSierra4x4 · November 20, 2015

Searched before posting...

2015 GMC Sierra 4x4 Crew Cab, Short Bed 5.3L & 3.42 rear end

Has anyone figured out a way to turn off the AC compressor using automatic climate control? Per my selling dealer, the AC compressor runs in any setting manual or automatic except for manual mode with the vent set to face only. My city mileage jumped about 2 MPG after driving around in manual with the vent set to face. I have about 5400 miles and manually calculate fuel mileage every tank.

In Auto Climate, the entire automatic climate system shuts off when I turn off the AC which prevents the fan speed from controlling temperature. My Honda Pilot is the same way, but I can select Auto Climate and manually turn off the AC by pushing to button. The auto fan control still works.

Thanks.

RubySilverado · November 24, 2015

Another issue I have with the climate control stuff is that even when it is off, there is still air flowing through the vents. I would like to know how to make that stop

davidio840 · November 24, 2015

Another issue I have with the climate control stuff is that even when it is off, there is still air flowing through the vents. I would like to know how to make that stop

I to am curious about this.

fondupot · November 24, 2015

RTFM. It is explain there I believe.

In Auto mode, the AC light comes on, but doesn't necessarily mean the compressor is running.

And when the system is off, hit the "inside" recirculate button to make the air stop coming in the vents.

TJay74 · November 24, 2015

When you turn the system off and the recirculate mode is set to outside air then as you drive the outside air is hitting the intake location and being directed into the cab, as said if you don't want that turn the recirculate on or close the vents.

I didn't like how the auto mode worked on my 2014 so I had the new update for the HVAC module flashed into mine, this makes it work like prior GM vehicles.

redwngr · November 26, 2015

Think of the AC light as 'ac enabled' rather than 'ac compressor on'.

The compressor will cycle on and off as necessary, without switching the light on/off.

GMCSierra4x4 · November 30, 2015

RTFM. It is explain there I believe.

In Auto mode, the AC light comes on, but doesn't necessarily mean the compressor is running.

And when the system is off, hit the "inside" recirculate button to make the air stop coming in the vents.

Wow... a response from the guy in high school who always had the right answer until he got it wrong on the test.

I have read the owner's manual and it does not explain the operation other than: AC light means the system is enabled in Auto, but does not tell you when it is running. Fan manually turned off and the AC is off even when selected....brilliant got that one too. Select a vent setting on the console in Auto and the Auto system turns off...great and obvious.

So, here is what I know: Outside air temperature between 30-50 degrees using Auto. My fuel mileage is 13.5 mixed driving. Vent (face mode) selected in manual and my mileage is 15.2 mixed driving, so the compressor is obviously running more often than not.

ON EDIT: Interstate driving (2 hrs.) with speeds averaging 65-70 MPH. Auto Mode: 19.7 MPG, Manual Mode (Face vent): 20.9

Filled up at the same Costco before and after each trip. So, I assume the compressor is running in defrost mode at least part time without any indication.