Is Automatic Climate Control really designed to be this stupid?

ember1205 · December 1, 2025

I have a 2024 Silverado RST that I bought new after owning my 2015 Silverado LT from new (and driving for 100k miles). The climate control has always irritated me in the cooler weather because it has NEVER worked as I would expect but the local dealer can't find any codes with the scanner so they just keep claiming it's working as designed. Is it, though? Did GM -REALLY- design it this stupidly? Or am I completely missing something?

For my specific climate controls, from the manual:

Quote

Automatic Operation

The system automatically controls the fan speed, air delivery, air conditioning, and recirculation in order to heat or cool the vehicle to the desired temperature.

When AUTO is lit, all four functions operate automatically. Each function can also be manually set and the selected setting is displayed. Functions not manually set will continue to be automatically controlled, even if the AUTO indicator is not lit.

A few paragraphs later, it explicitly states that change the Air Delivery Mode Control disables Automatic operation and states that the "system goes into manual mode."

Today, it was 40 degrees outside (Fahrenheit). I started the truck and have the Automatic mode enabled with the temperature set to 70 degrees. A few minutes after it starts blowing warm air into the cabin, the top vents open and I have cooler air now blowing directly on me. My 2015 -NEVER- did this in Automatic mode and I end up feeling cold because of that air blowing directly on me. If I change the air handling to be footwell only, the manual seems to indicate that I will lose the temp maintenance function of the Automatic setting.

Further, there is a setting in the Infotainment to set the fan speed for Automatic mode to Low, Medium, or High. This does not seem to be a limit and appears to be a fixed fan speed setting for when it is operating in Automatic mode (it never changes in the cold weather, although it DOES run on a few different speeds when it's hot and I'm running the A/C) and is in direct conflict with the statement in the manual about how Automatic mode controls fan speed.

This -HAS- to be dumbest design of an automatic climate control system ever. Why in the world did GM do this?

More importantly, how can I actually get automatic temperature AND fan speed control at all times without getting hit with cold air during cold temps?

Atlas · December 2, 2025

I hate automatic climate control, and having dual-zones is the worthless icing on top. It's a truck cab, not a multi-level mansion. Give me back 3 knobs. Vent setting, temperature, and fan speed. That's all I need. If a passenger is too hot or cold, they can ask to change the settings, or walk-- I don't care.

In my experience, it's true: Changing anything while the system is in "auto" mode causes it to no longer be in "auto" mode.

I think the owner's manual is a bit word-salad and should use the descriptors "static" and "dynamic". All controls are dynamic (changing) in true "auto" mode. Auto mode is disabled when any single control other than temperature setting is manually changed. The controls then retain their last setting as static (automatic, but not dynamic). The system will continue heating or cooling at your target temperature with a fixed vent position and fan speed if you've changed something that knocks it out of automatic mode.

I understand the fan setting in the infotainment to be a maximum for auto mode. It can use any of the lower fan speeds as necessary, but if you fire up the truck on a hot day and set "auto" mode to freeze you out, it can only use the maximum fan speed selected in infotainment. I have mine set to medium because high is just too loud/obnoxious. I think this also controls the remote start HVAC fan speed. That's another level of dumb. I'd use it more if I parked the truck outside but I don't.

I rarely use auto mode. For heating, I have it set on floor vents only, A/C turned off, set to 72 degrees. For cooling, I use bi-level vent mode (dash and floor vents, not defrost vents) set to 'LO' temperature (minimum) on whatever fan speed depending on how warm I am when I get in the truck and then adjust later.

Again, why can't we just have 3 knobs (at least as an option for those of us who prefer simplicity)

Edited December 2, 2025 by Atlas

asilverblazer · December 2, 2025

I've found that there is a fine line between the truck thinking you need to be cooled versus warmed. In the summertime I am usually able to set the temperature below 72 and it functions as expected. In the winter time I set it at 74 and results are as expected. I notice that I cannot leave it at the 72 degree setting, because it continues to perform like I need to be cooled.

Summer temperature setting 70 winter setting 74 - and this keeps me comfortable.

The only time I fine tune the temperature is after several hours of driving like on a long trip, where up or down 1 degree seems to perform well.

ember1205 · December 2, 2025

1 hour ago, asilverblazer said:

I've found that there is a fine line between the truck thinking you need to be cooled versus warmed. In the summertime I am usually able to set the temperature below 72 and it functions as expected. In the winter time I set it at 74 and results are as expected. I notice that I cannot leave it at the 72 degree setting, because it continues to perform like I need to be cooled.

Summer temperature setting 70 winter setting 74 - and this keeps me comfortable.

The only time I fine tune the temperature is after several hours of driving like on a long trip, where up or down 1 degree seems to perform well.

Similar here, except I want 70 year-round. Works fine in the warm weather when I need A/C, but it's HORRID in the cold weather and it constantly switches on the vents and blows cool air making it extremely uncomfortable. I can't even tolerate moving the temp to 71 or 72 as I sweat my a** off with that setting.

This is a horrendous configuration and the way it ACTUALLY operates does not match what the manual states. And since there are "no codes", no one can (or will) do anything about it at the dealership. The ability to troubleshoot and diagnose no longer exists... everyone is a keyboard monkey now that is only able to follow directions from service bulletins that are linked to a trouble code.

asilverblazer · December 2, 2025

16 hours ago, ember1205 said:

A few paragraphs later, it explicitly states that change the Air Delivery Mode Control disables Automatic operation and states that the "system goes into manual mode."

Today, it was 40 degrees outside (Fahrenheit). I started the truck and have the Automatic mode enabled with the temperature set to 70 degrees. A few minutes after it starts blowing warm air into the cabin, the top vents open and I have cooler air now blowing directly on me. My 2015 -NEVER- did this in Automatic mode and I end up feeling cold because of that air blowing directly on me. If I change the air handling to be footwell only, the manual seems to indicate that I will lose the temp maintenance function of the Automatic setting.

I've always assumed it was completely manual operation if the "Auto" light isn't on.

16 hours ago, ember1205 said:

Further, there is a setting in the Infotainment to set the fan speed for Automatic mode to Low, Medium, or High. This does not seem to be a limit and appears to be a fixed fan speed setting for when it is operating in Automatic mode (it never changes in the cold weather, although it DOES run on a few different speeds when it's hot and I'm running the A/C) and is in direct conflict with the statement in the manual about how Automatic mode controls fan speed.

I think this is like a general setting - in my case I don't like to hear the fan blowing real hard, and only on the hottest days do I want to increase the fan speed manually. In automatic mode it uses a 'slower' fan speed vs. where some might like more air flow and a 'faster' fan speed. I don't think this setting otherwise changes how the climate control operates beyond a baseline fan speed that the climate control works from.

newdude · December 2, 2025

74F is typically the limit to keep heat in cold outside temps but not roast you out of the cabin.

I typically will start in AUTO and then control the fan speed. Everything else will remain in AUTO mode except for fan speed so if you set the temp to HI, it will alter the temp doors for full hot and change the air vent positions accordingly but you control the fan speed.

IMO, AUTO works pretty good once you start to play around with it and figure out what its limits are and what its capable of. There are times for sure where you want some amount of manual control with it though.

As for why AUTO does what it does, its all based on various data inputs from sensors. Note below that one of the sensors is the ambient light/sunload sensor. If its 30F outside but its sunny, the sun is still affecting that load sensor, so the vehicle can detect a rise in temps from that and start to swing the doors to pull in cooler air:

Automatic Operation

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

The automatic mode indicator shows that the system is in full automatic operation. If an individual setting is changed (excluding temperature), the automatic indicator will turn off, and that function will enter manual control. All other functions will remain under automatic control unless manually changed.

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

The auto switch must be activated.
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 BCM performs the following functions to maintain the desired air temperature:

Monitors the following:
- Ambient (outside) air temperature sensor
- Passenger compartment temperature sensor
- Calculated front duct air temperatures
- Windshield temperature and inside moisture sensor
- Evaporator temperature sensor
- Ambient light/sunload sensor
Regulate the blower motor speed
Position the air temperature actuators
Position the mode door actuators
Position the recirculation actuator
Control of the A/C compressor solenoid

Edited December 2, 2025 by newdude

ember1205 · December 2, 2025

14 minutes ago, asilverblazer said:

I've always assumed it was completely manual operation if the "Auto" light isn't on.

I think this is like a general setting - in my case I don't like to hear the fan blowing real hard, and only on the hottest days do I want to increase the fan speed manually. In automatic mode it uses a 'slower' fan speed vs. where some might like more air flow and a 'faster' fan speed. I don't think this setting otherwise changes how the climate control operates beyond a baseline fan speed that the climate control works from.

I also always believed it was either Auto (light on) or not... The manual states that is not actually the case as adjusting some settings don't deactivate auto mode in its entirety, but then it says that if you change the setting for where the air is delivered from it DOES completely disable auto made.

The fan speed for Automatic mode makes absolutely no sense. Why would I want to set a specific fan speed in Auto mode when Auto mode clearly states it adjusts the fan speed on its own? The entirety of the configuration controls makes zero sense when you look at it holistically. And it definitely does NOT work like vehicles of the past where it either operated fully automatically (including shutting the fan OFF if warranted) or you managed the settings manually. This is just another boneheaded design decision made by GM that further demonstrates their complete incompetence at software design... Yet, they're going to compeltely shove their software down our throats soon...

ember1205 · December 2, 2025

2 minutes ago, newdude said:

74F is typically the limit to keep heat in cold outside temps but not roast you out of the cabin.

I typically will start in AUTO and then control the fan speed. Everything else will remain in AUTO mode except for fan speed so if you set the temp to HI, it will alter the temp doors for full hot and change the air vent positions accordingly but you control the fan speed.

As for why AUTO does what it does, its all based on various data inputs from sensors:

Automatic Operation

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

The automatic mode indicator shows that the system is in full automatic operation. If an individual setting is changed (excluding temperature), the automatic indicator will turn off, and that function will enter manual control. All other functions will remain under automatic control unless manually changed.

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

The auto switch must be activated.

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 BCM performs the following functions to maintain the desired air temperature:

Monitors the following:

Ambient (outside) air temperature sensor

Passenger compartment temperature sensor

Calculated front duct air temperatures

Windshield temperature and inside moisture sensor

Evaporator temperature sensor

Ambient light/sunload sensor

Regulate the blower motor speed

Position the air temperature actuators

Position the mode door actuators

Position the recirculation actuator

Control of the A/C compressor solenoid

Thanks for these details... There is absolutely no way I can drive my truck with the temp set to 74 degrees without being in shorts and a T-shirt, and even then I would be way too hot.

The "monitors" section is interesting as it seems to further reinforce that the design of this system is bad.

- I know the external air temp sensor for my truck is wrong. It read at least four degrees higher than it really is at all times. Dealer refused to do anything about it during multiple visits.

- "Calculated" temperatures is not measured.

- Ambient light is not a good way to measure heat load. Bright does not mean direct sun, nor does direct sun mean that it's direct on -me- (as opposed to direct on the sensor which is all the way at the front of the dash).

After two full years of driving this truck, I still can not figure out how to set the HVAC controls to be comfortable in the spring or the fall (which amounts to half the time I drive the truck since I drive the car more in the summer when the HVAC seems to work ok).

newdude · December 2, 2025

2 hours ago, ember1205 said:

- Ambient light is not a good way to measure heat load. Bright does not mean direct sun, nor does direct sun mean that it's direct on -me- (as opposed to direct on the sensor which is all the way at the front of the dash).

After two full years of driving this truck, I still can not figure out how to set the HVAC controls to be comfortable in the spring or the fall (which amounts to half the time I drive the truck since I drive the car more in the summer when the HVAC seems to work ok).

Its using the sunload function of that sensor, not the ambient light. The light side is related to auto headlamps and the dash lighting during the day.

ember1205 · December 2, 2025

30 minutes ago, newdude said:

Its using the sunload function of that sensor, not the ambient light. The light side is related to auto headlamps and the dash lighting during the day.

That's fine, but again... that sensor being in direct sun doesn't mean I am. And even if I am, it doesn't mean anywhere else in the cabin is. The way the system is making decisions on what areas to warm or cool clearly shows that the algorithm being used needs improvement.

Jus Cruisin · December 2, 2025

I'm good with the auto climate control in both the 2023 and the 2025. Both keep me comfortable at 73°year around. My wife keeps the passenger side at 72°. We rarely adjust the temps.

asilverblazer · December 2, 2025

2 hours ago, ember1205 said:

- I know the external air temp sensor for my truck is wrong. It read at least four degrees higher than it really is at all times. Dealer refused to do anything about it during multiple visits.

Try replacing the sensor.

asilverblazer · December 2, 2025

20 hours ago, ember1205 said:

Today, it was 40 degrees outside (Fahrenheit). I started the truck and have the Automatic mode enabled with the temperature set to 70 degrees. A few minutes after it starts blowing warm air into the cabin, the top vents open and I have cooler air now blowing directly on me.

Getting back to your problem vs. how the system is engineered.

It sounds like at the temperature set point you started feeling cold, why not raise the temperature set point? As I stated earlier, if I use this set point my truck seems to more readily try to cool me.

GM has for a long time now assumed you want heat from the floor and cool from the dash. All my AUTO climate controls have behaved this way as far back as 93.

ember1205 · December 2, 2025

3 minutes ago, asilverblazer said:

Getting back to your problem vs. how the system is engineered.

It sounds like at the temperature set point you started feeling cold, why not raise the temperature set point? As I stated earlier, if I use this set point my truck seems to more readily try to cool me.

GM has for a long time now assumed you want heat from the floor and cool from the dash. All my AUTO climate controls have behaved this way as far back as 93.

Raising the temp even by one degree makes it too warm in the cabin. And it completely defeats the intent of "auto" if I have to manually override it.

The system in my 2015 worked correctly, year-round. This setup is terrible.

ember1205 · December 2, 2025

11 minutes ago, asilverblazer said:

Try replacing the sensor.

Dealer won't do anything with it. No codes, no problems. That's how it goes now. I had to fight with them to replace a warped piece of plastic on the backside of my steering wheel when I first bought the truck. They kept claiming "all of the other trucks on the lot" were exactly the same. I told them I wanted to have the lead mechanic come out.. After I ran his hand along the very sharp piece of plastic that was protruding, he finally admitted it was dangerous and figured out how to get it repaired.

And this dealership is actually one of the better ones in terms of their work (even though they short-filled my oil when they changed it... idiots). And the local GMC dealer told me point blank they will not work on any vehicle they didn't sell even though the GM warranty actually entitles me to have it serviced there.