Auto Temperature/Fan Doesn't Seem Too Intelligent

[mopac]

I'm continuing to play with this.  

 

I think I'm understanding the auto fan setting LO-MED-HIGH in the infotainment settings.  I think it might be better labeled SLOWER-NORMAL-FASTER.  I think it works as a modifier for the fan speed the computer would otherwise select based on outside temp, inside temp, sun loading from the dash sensor etc.  The MED or "NORMAL" setting is essentially just whatever the computer would choose for the fan speed.  LO or "SLOWER" just tweaks down the speed the computer would otherwise have selected and HIGH or "FASTER" just tweaks up the speed the computer would have selected.  I think it's meant to "dial in" your comfort relative to the "standard" person the computer is programmed for.

 

I'm also now questioning whether the system might be slow to recognize a change in outside temperature from when the car was turned off.  So if you turn it off at 5pm at the outside temperature is 60 and overnight a cold front moves in and when you go to start the vehicle and its 31 outside perhaps for a few minutes the computer still thinks it's 60?   I'm also wondering if the fast fan speed when I started it a few days ago could have been user error in my canceling auto control accidentally.  Selecting any of a number of HVAC buttons on the dash can have the effect of cancelling auto control.  Perhaps I did that.  This morning at least, it did seem to be working more along the lines of the Nissan.  

[TJay74]

OP you are talking about 2 different system and events here. There is the fan speed for when under a remote start event, that is in the infotainment system. You set that speed and then based on the temp you leave the truck set at the truck will based on outside ambient temps decide if it needs AC or Heat.

The "Auto" on the HVAC system is for once the truck is power up and on with the key in the on position, then the system will take over control of the fan speed and such based on the temperature sensors in the system.

[mopac]

2 hours ago, TJay74 said:

OP you are talking about 2 different system and events here. There is the fan speed for when under a remote start event, that is in the infotainment system. You set that speed and then based on the temp you leave the truck set at the truck will based on outside ambient temps decide if it needs AC or Heat.

TJay74 - I have to disagree based on my playing around with these settings.  Try it yourself on your 16 Sierra.  Go into the infotainment system and set the auto fan speed to low.  (I think the truck needs to be running to change this or at least with key in on position)  Then remote start you vehicle and you should still have the fan going at the highest speed until you put the key into the ignition and turn it to on.  At that point the fan will immediately slow down.  The fan is on high under a remote start for my 18 Silverado no matter what I set the infotainment auto fan to.  But once I put the key in and turn to on then the fan speed will vary depending on what I have the auto fan speed in the infotainment set at.  Try it.

[STRMTRPR]

  I have to agree with the OP regarding the "Auto" climate control on these trucks.. this is my one big complaint about my truck.. (my first GM truck).. this is hands down the worst functioning system I've ever used.. all my vehicles have had ATC since my first '86 Lincoln.. and even that '86 Lincoln -32yrs earlier technology- was far superior. I will also agree with the comment regarding the Grand Cherokee ATC - this was the most refined well functioning setup I've used - GM would do well to learn from Jeep/Chrysler here - my first Grand Cherokee was an '01 and again even that 17yr earlier technology put the GM tech to shame.

  Don't get me wrong I do love this truck as a truck but the tech is far behind.

[colonel00]

On 11/10/2018 at 9:48 AM, mopac said:

I think I'm understanding the auto fan setting LO-MED-HIGH in the infotainment settings.  I think it might be better labeled SLOWER-NORMAL-FASTER.  I think it works as a modifier for the fan speed the computer would otherwise select based on outside temp, inside temp, sun loading from the dash sensor etc.  The MED or "NORMAL" setting is essentially just whatever the computer would choose for the fan speed.  LO or "SLOWER" just tweaks down the speed the computer would otherwise have selected and HIGH or "FASTER" just tweaks up the speed the computer would have selected.  I think it's meant to "dial in" your comfort relative to the "standard" person the computer is programmed for.

This is my understanding as well.  The Auto Fan Setting throttles or governs or as you aptly put it, modifies the speed that the fan is allowed to blow.  On my truck, if I set this setting to Low and the fan will not blow with as much intensity as it would set to Med or High when it is trying to overcome a large temp difference between the ambient temp and your set temp.  I usually have it set on High actually and don't notice any issues though it hasn't gotten really cold here yet.  In the summer though it is great as it cranks the AC and cools the cab quickly blowing "Max".  

 

As a similar example of this throttling, when you get a call over BT, the fan will slow down to lessen noise on the call.  The system "wants" to blow harder but is governed to a lower speed.  It is still working to achieve the wanted temp but it will just take longer blowing slower.  

 

Really, the only "complaint" that I have is that I usually have the temp set at 72 in the summer and 70 in the winter to achieve the same comfort level for me.  But, that's just how the system interprets the temps and I can deal with that just fine.

Edited November 11, 2018 by colonel00

[sk]

On 11/11/2018 at 1:34 PM, colonel00 said:

This is my understanding as well.  The Auto Fan Setting throttles or governs or as you aptly put it, modifies the speed that the fan is allowed to blow.  On my truck, if I set this setting to Low and the fan will not blow with as much intensity as it would set to Med or High when it is trying to overcome a large temp difference between the ambient temp and your set temp.  I usually have it set on High actually and don't notice any issues though it hasn't gotten really cold here yet.  In the summer though it is great as it cranks the AC and cools the cab quickly blowing "Max".  

 

As a similar example of this throttling, when you get a call over BT, the fan will slow down to lessen noise on the call.  The system "wants" to blow harder but is governed to a lower speed.  It is still working to achieve the wanted temp but it will just take longer blowing slower.  

 

Really, the only "complaint" that I have is that I usually have the temp set at 72 in the summer and 70 in the winter to achieve the same comfort level for me.  But, that's just how the system interprets the temps and I can deal with that just fine.

I agree this is the way it works.  The "fan speed" selection in the radio settings will limit how fast the fan will blow when the truck is running and the climate control is set to "auto".  Some people don't want the air blowing on them at high (or the noise it makes) so GM gives you the option to set max fan speed to low or medium.  Again -- this only applies when the truck is running and the "auto" button is set.

 

Any time you remote start the fan will blow at the highest setting if it needs to.  The system assumes nobody is in the vehicle if you are doing a remote start so it doesn't worry about keeping the airflow low until it either warms (heat) or cools (AC).  It just goes full blast to try to heat or cool the vehicle quickly.  The "auto" setting does not apply during remote start and the light on the knob will not be lit up but if you had auto on the last time you drove the vehicle it will resume those settings once you put the key in and turn the ignition.  Also if you have heated seats they will run on the highest setting during a remote start but the light on the switch will not be on.  Once you get in the truck and turn on the ignition you can use the switches to put them at the setting you want.

 

And like you said -- if you touch any button (other than the temp dial) to change an HVAC setting the system will automatically take it out of "auto" and the light will go off.  The truck remembers this setting so if you don't turn auto back on it will still be off the next time you get in the truck. 

[t777jb]

My $20K 2007 Mazda 3 had climate control and I never had to touch it - never.  It knew if the windows needed defrosted and changed between recirculate or fresh air - it did everything - genius.  Then I bought a $32K 2015 VW GTI and it didn't even have climate control - ridiculous.  You had to spend another $2k to get climate control and nav.  I just traded the GTI in on a 2018 Sierra SLT and the climate control and the heat in general both suck.  I'm constantly fiddling with it which means it's not auto at all.  Furthermore the vents to defrost the windshield don't extend all the way across so the bottom corners of the windshield take forever to clear.  I enjoy driving the truck and like many of the features, but it is mind blowing  that they got so many things wrong in the 5th year of this generation of truck.  The transmission and climate control must be run by the same computer cause neither one of them knows what they are supposed to be doing.  I'm not ready to say I'm stuck with it now cause there are things I do like about it, but after just 2 months of ownership, I'm not sure I would make this purchase again.  

[20165.3Eco]

Yep, I also am dumbfounded that testing didn't show them the defroster vent is grossly inadequate for clearing the lower corners of the windshield.

 

I mean, guys who do this for a living designed this stuff and guys who are just average Joe truck owners can pick out faults withing minutes of operating. 

[15 Z71]

Mine works good at 73 now that winter is coming....but sometimes I actually have to move my finger to push the defrost button. It's not easy but I manage to.

[roadkill5.3]

I’ve noticed while in “auto” mode, I can change the vent locations, recirc, ac, and fan speeds, while still staying in “auto”. 

Maybe you have the fan speed “manually” set while in “auto” mode?

 

Take it out of auto and put it back in

 

i leave mine set at 70, auto mode, AC manually on, vents to feet and windshield, recirc set to outside air, and don’t touch the fan speed knob. The fan will ramp up and down automatically, while keeping the AC on for dehumidification, air won’t be blown at my face or hands, while having fresh air intake. Best setup I found. 

  remote start will be full speed, until key goes in and turned. Phone calls will have the fan slow down. The auto fan setting in the menu is for the fan speed once the temp is “satisfied” in the truck. I have mine on low. If it’s satisfied, why run high, or medium? The temp has already been achieved...

[Capt Bob]

When you (or anyone else) states that the fan speed is on high when remote starting, does the position of the manual fan switch come into play?  Also, I'm assuming that one knows it is blowing on the high setting because that is what is felt when you first open the door and enter the truck, correct? This doesn't appear to be the case with mine but we haven't had the large temperature swings that others are seeing. Tomorrow we'll see morning lows just above freezing so maybe I'll find the fan on high when I open the door.

 

I'm set on the low auto position on the screen but my manual switch is not set on high (or at least rotated enough to set the highest speed manually) so maybe that is why mine is on low when I enter?

 

Interesting. Hey it's my first programable AC.

[colonel00]

On 11/13/2018 at 7:52 PM, Jgreen2193 said:

I’ve noticed while in “auto” mode, I can change the vent locations, recirc, ac, and fan speeds, while still staying in “auto”. 

Maybe you have the fan speed “manually” set while in “auto” mode?

 

Take it out of auto and put it back in

 

i leave mine set at 70, auto mode, AC manually on, vents to feet and windshield, recirc set to outside air, and don’t touch the fan speed knob. The fan will ramp up and down automatically, while keeping the AC on for dehumidification, air won’t be blown at my face or hands, while having fresh air intake. Best setup I found. 

  remote start will be full speed, until key goes in and turned. Phone calls will have the fan slow down. The auto fan setting in the menu is for the fan speed once the temp is “satisfied” in the truck. I have mine on low. If it’s satisfied, why run high, or medium? The temp has already been achieved...

That just sounds odd.  What year and model/trim do you have?  On my '18 Silverado LT, when it is in Auto with the left know illuminated, if I press any other buttons the Auto shuts off.

[MaverickZ71]

Part of the problem may be that GM puts their outside temperature sensor right in front of the radiator, and as such, has programmed it to be slow in reacting to warming temps, because they are worried about false readings due to heat soak.  Not sure if they fixed it on the new models (knowing the General, probably not), but on the GMT900s, the outside temp sensor would update once a minute at highway speeds.  Around town, it wouldn't update unless certain conditions were met, above 45 mph, so many minutes since key on, etc.  So if you were driving slow around town with multiple stops, it might be a very long time to reset the outside temp from the first reading of the day at first startup.  There have been more than a few days where it was freezing in the morning and warmed up to 50+F in the afternoon and we were driving around town with my auto HVAC still blowing heat full blast in the afternoon, and we were about to smother.  Then I did some online research and discovered how to reset the system--you'd press the A/C button and Recirc button at the same time, and it would instantly do a force reset of the outside temp sensor, and then the Auto HVAC could work properly.  

Edited November 15, 2018 by MaverickZ71

[roadkill5.3]

9 hours ago, colonel00 said:

That just sounds odd.  What year and model/trim do you have?  On my '18 Silverado LT, when it is in Auto with the left know illuminated, if I press any other buttons the Auto shuts off.

That’s correct!

but if you actually press a button, you’ll see that the other settings are still in auto. 

Example

press auto. Ac will be on auto, blower direction will be auto, fan auto, fresh air intake or recirc auto. Everything will be in auto. 

Press the recirculate button or any button. You will see that the fan will still be in “auto” and now it will bring in fresh air due to you changing the setting. The display for the hvac will pop up and tell you the status of each control. Hard to explain.  Jump in your truck, and turn auto off (if it’s already on) and back on, then change the blower direction or something. You’ll see it. Until you change the fan speed, the fan will stay “auto”, or any other feature from being auto controlled,  even though the light is “off”, the settings you did not touch will be in auto still. 

2016 lt silverado

 

Edited November 15, 2018 by Jgreen2193

[mopac]

OK, I may owe GM an apology as this thing might be more "intelligent" than I originally gave it credit for.  But I would say it's certainly not intuitive, nor is it explained very well for having manuals that are a couple inches thick.  

 

I did really appreciate the earlier comment today about pressing AC and Recirc buttons simultaneously to reset the outside temp sensor.