AUTO A/C Setting

[Trey Beck]

So this may be the dumbest thing GM does.  If I use the auto function for the A/C (I always run the AC being in Florida) it shuts off the recirculating function for the A/C.  This then lets hot moist air into the cab.  My question, is there a way to use the auto function and still have the regulating function stay on?  My Toyota would do the same thing but after you hit auto you could turn the recirculating function on and it would still stay in Auto mode.  This was in a 2010 Highlander.  

[GN2018]

If you start by hitting Auto, it will essentially stay in Auto mode if you hit the recirculating button.  It will still hold the temp and control the fan automatically.  The Auto light will just not be on.  I do this all the time.  Same thing happens if you hit the buttons to redirect the airflow.  I guess it basically stays as automatic as you let it.

[Silverado4x4]

As GN2018 said as I was getting ready to type the same thing. The problem I had was the wife she would always turn the right temp control knob and take it out of sync then I would have to resync it hit auto then turn on recirc, she finally stopped doing it. I hated when she would do that because the left and right temp knobs would be different temp settings. 

Edited May 1, 2025 by Silverado4x4

[newdude]

In AUTO the system is automated.  Set the temp and the doors and fan will move accordingly based on the temp you set and then the in cabin sensors like the windshield moisture sensor, sunload sensor and HVAC duct sensors.  

 

Recirc door is controlled during AUTO as well.  You can command it independently as well but otherwise in AUTO it will control it.    

 

Automatic Operation

In automatic operation, the HVAC control module maintains the comfort level inside of the vehicle by controlling the A/C compressor clutch, the blower motor, the air temperature actuators, mode actuator and recirculation actuator.

To put the HVAC system in automatic mode, the following is required:

1. The auto switch must be activated.
2. The air temperature switch must not be in either the full hot or full cold position.

Once the desired temperature is reached, the blower motor, mode, recirculation and temperature actuators automatically adjust to maintain the temperature selected. The HVAC control module performs the following functions to maintain the desired air temperature:

• Monitors the following sensors:
  • Ambient air temperature sensor
  • Ambient light/sunload sensor
  • Windshield temperature and inside moisture sensor
• Regulate the blower motor speed
• Position the air temperature actuators
• Position the mode door actuator
• Position the recirculation actuator
• Request A/C operation
• Control of the A/C compressor

When the warmest position is selected in automatic operation the blower speed will increase gradually until the vehicle reaches normal operating temperature. When normal operating temperature is reached the blower stays on high speed and the air temperature actuators stays in the full heat position.

When the coldest position is selected in automatic operation the blower stays on high and the air temperature actuators stay in full cold position. The mode actuator remains in the panel position and the recirculation actuator will remain in the recirculation position.

Under cold ambient temperatures, the automatic HVAC system provides heat in the most efficient manner. The operator can select an extreme temperature setting but the system will not warm the vehicle any faster. Under warm ambient temperatures, the automatic HVAC system also provides air conditioning in the most efficient manner. Selecting an extreme cool temperature will not cool the vehicle any faster.

 

 

 

Recirculation Operation

The recirculation switch is integrated into the HVAC control. The selected recirculation setting is sent to the HVAC control module via LIN-Bus. The HVAC control module controls the air intake using the recirculation actuator. In recirculation mode the recirculation door is positioned to block outside air from entering and circulate the air within the vehicle. In outside air mode the recirculation door is positioned to route outside air into the vehicle.

Recirculation is available in vent and vent/floor mode.

In floor only mode, some airflow is directed to the defrosters. In defrost and floor only modes, the actuator positions the recirculation door so that outside air is circulated to reduce window fogging.

In automatic mode the values of the sensors are used as inputs for the HVAC control module to calculate the fog risk on passenger compartment side of the windshield. The A/C compressor and the defrost mode may activated to prevent or remove fog on the passenger compartment side of the windshield.

Edited May 1, 2025 by newdude

[PunchT37]

Tried mine 5 times today. From off, hit auto and full low on temp. Thing starts blasting. No recirc light. If you hit recirc, the light comes on with no difference in sound. Hit recirc again, light goes off with a difference in sound. Hit recirc again, light comes on with a difference in sound. Off, it repeats.

 

 So, from off, it controls recirc, with no light in auto. Once you hit the recirc button, it`s "in your hands now" even though the auto light is still on.

 

Tried out of temp sync mode. Still the same.

[Silverado4x4]

If it's hot inside the cab with it on low it will blast until the temp inside is met where you have it set when it is met the fan will slow down when in auto same with heat. Also there is a setting in the Infotainment under climate control where you can pick high medium or low fan speed. So hit sync,auto,hit recirc to turn off and adjust your temp control knobs.

 

Edited May 1, 2025 by Silverado4x4

[newdude]

1 hour ago, PunchT37 said:

Tried mine 5 times today. From off, hit auto and full low on temp. Thing starts blasting. No recirc light. If you hit recirc, the light comes on with no difference in sound. Hit recirc again, light goes off with a difference in sound. Hit recirc again, light comes on with a difference in sound. Off, it repeats.

 

 So, from off, it controls recirc, with no light in auto. Once you hit the recirc button, it`s "in your hands now" even though the auto light is still on.

 

Tried out of temp sync mode. Still the same.

 

 

Correct, in AUTO the light won't display.  If you went into the "Climate" page on the radio however it will show you what is all labeled as AUTO for its function.  

 

AUTO = set the temp, truck does the rest.  Changes the mode doors, fan speed and recirc doors all on its own.  

Edited May 1, 2025 by newdude

[GN2018]

5 hours ago, Silverado4x4 said:

As GN2018 said as I was getting ready to type the same thing. The problem I had was the wife she would always turn the right temp control knob and take it out of sync then I would have to resync it hit auto then turn on recirc, she finally stopped doing it. I hated when she would do that because the left and right temp knobs would be different temp settings. 

I hate it when my wife turns down the fan using the fan control knob.  If I want the fan, I adjust it by changing the temp.  I like the automatic fan as part of Auto.

[Silverado4x4]

7 minutes ago, GN2018 said:

I hate it when my wife turns down the fan using the fan control knob.  If I want the fan, I adjust it by changing the temp.  I like the automatic fan as part of Auto.

I agree with that 100% I forgot about that one took me about 1 week to break her of the fan control knob. Then it moved to the Tahoe everytime I got in it the climate control would be all out of wack but all good now. I told her after getting everything back to normal all you have to do is adjust the left knob and don't touch the right knob for temp up or down the vehicle will take care of the rest.

Edited May 1, 2025 by Silverado4x4