[Nebula1701]

You haven't given the 12V enough time to charge.... It may take a bit and it could be a weak 12V....

I've seen all of the above issues with random lights or odd things happening in the Chevy Volt community all due to 12V issues.

 

[Nebula1701]

The HV battery should be used for cooling, the HVAC compressor is normally 400V, not 12v on EVs. The blower motor for cabin cooling will be 12V.

Here is a photo of a Bolt AC compressor, notice the orange wires, meaning high voltage.

View attachment 3189

The 12V is still used to wake the vehicle up and power the computers to do that job.

 

[Nebula1701]

Bare minimum I’d hope they’d have the truck send a notification when the 12v battery gets low instead of it being a complete surprise. Ideally, there’d be a routine that checks the 12v at a certain interval, and has it kick on the HV system to recharge itself so that it never strands you or ends up dead.

As far as I can tell the Hummer only checks the 12V voltage once a day.