Constant 'Max Defog' - makes a hot hell

[CaptainTom]

Last night the climate system on my 2025 Tahoe self-switched to "Max Defog" and temp settings of 76 degrees F. The system would not respond to any of the manual physical knobs/buttons or the touchscreen inputs, except the OFF button would shut the system down...then after ten seconds, the system restarted, again Max Defog/76 degrees. and again, and again...

I parked for awhile to let the car cool off in the 25 degree weather, while reading the climate control section of the manual. It mentioned an "auto defog" setting which I found and set to off.

I restarted and bang "Max Defog" again...and again...and again. I took the car home and left it.

Today the problem is gone. Any ideas or advice?

 

[2024 White Tahoe]

Last night the climate system on my 2025 Tahoe self-switched to "Max Defog" and temp settings of 76 degrees F. The system would not respond to any of the manual physical knobs/buttons or the touchscreen inputs, except the OFF button would shut the system down...then after ten seconds, the system restarted, again Max Defog/76 degrees. and again, and again...

I parked for awhile to let the car cool off in the 25 degree weather, while reading the climate control section of the manual. It mentioned an "auto defog" setting which I found and set to off.

I restarted and bang "Max Defog" again...and again...and again. I took the car home and left it.

Today the problem is gone. Any ideas or advice?

I don’t have any ideas advice but have a similar problem.

I have a 2024 Tahoe Premier 4WD, purchased new. I set the rear HVAC control to SYNC with the front (using the front touch screen).

Since new, every several days when I start the vehicle, the SYNC feature is turned off, and the rear HVAC controls are switched to manual - with the rear blower on high. If I use the screen controls to SYNC the rear to the front, it responds.

I leave the front control screen on the sound system. Also, every several days when I start the vehicle, it displays the home screen. When I switch it to sound, it responds.

Another software issue I have is that intermittently, the beeping sound alert for the bumper sensors changes from the audible sound to the seat vibrate. I must change it back, and then several days later - it switches back.

It is clear there are some type of software defects that are causing my problem - and yours. No one else drives my vehicle, so the issues can’t be cause by someone changing the settings.

GM did a miserable job of software integration with the Tahoe and other vehicles. My wife purchased a new 2025 Equinox RS AWD and we have had repeated issues with the software, requiring multiple trips to the dealer for repairs.

Since my software issues are intermittent, I have not returned to the dealer for those issues. At my next oil change service, I will probably schedule an appointment for the issues.

 

[Dmay]

Last night the climate system on my 2025 Tahoe self-switched to "Max Defog" and temp settings of 76 degrees F. The system would not respond to any of the manual physical knobs/buttons or the touchscreen inputs, except the OFF button would shut the system down...then after ten seconds, the system restarted, again Max Defog/76 degrees. and again, and again...

I parked for awhile to let the car cool off in the 25 degree weather, while reading the climate control section of the manual. It mentioned an "auto defog" setting which I found and set to off.

I restarted and bang "Max Defog" again...and again...and again. I took the car home and left it.

Today the problem is gone. Any ideas or advice?

I am having the exact same issue this AM. Nothing I can do to reset it. My only guess is the cold temps are throwing the system off (13°). I have an appointment Friday and will see what the dealership says.

 

[CaptainTom]

This problem has not recurred since January 17 and last week the dealer installed a new control unit "Dash Control Unit - GM (85098832)" to address the root cause, under warranty of course. So we will see.

 

[LsHart]

In the older truck, hehe, that typically means head unit was bad. But with the new ones not sure. Scanner control the hvac system?