Digital HVAC system not powering up at all?

It is automatic digital climate control. I added a picture, actually 2 pictures. Or tried to, of the unit. I’ll try to send them again.

Here is a screen shot of the codes that my scanner gave me. I wasn’t able to hook to a Wi-Fi network where I scanned it at. I might be able to do that tomorrow. But if the codes that are shown in the pictures I have added, tell you anything, or she’s light on a certain procedure that I need to do, could you please let me know what to do?
Is it something that the scanner can fix?

Is it something that needs to be replaced?

I agree with you that it shouldn’t be a fuse, or an unconnected wire harness if the screen lit up for a second.
That’s why I shared that info with you.
Please let me know where to go from here, based on the scan codes listed in the pictures. Thanks again.

Justin H
If you can speak on the phone, please let me know, and I will send my cell number. Thanks

I sent 2 more emails for communication and haven't received anything back in almost 24 hrs. I just want to make sure I am posting to the correct spot.

I checked both fuses you highlighted. They are both good.
Key turned to accessories mode, 11.5 v reading from driver info cluster for battery voltage.

Both pins on each fuse showed 11.5v on them. So, no problems there.

I will check the alternator and report the findings, but I don’t believe this is the issue.
The HVAC problem started happening after I replaced a battery with a new one just weeks ago. The car had been completely drained of power for a few weeks.
Would this make a re-learn of any of the modules necessary?
That’s where I would need input for sure. But let me check this Alti, and report back so we can check that possibility off the list.
I do also have a battery drain somewhere, which I’m told could be a bad or near bad alternator.

Hang tight, Alti test coming up.

FYI, I haven’t been driving this on a regular basis. I start it and let it run for a few min, then shut it down.

Ran my Dewalt unit on Alternator test mode and it came up good as you can see in the picture. I the voltage when the car is on accessory mode (not running) was at 11.5v and when the car is started, with lights on, radio on, goes up to 14.7 range, and stays there until it’s turned off.

I can definitely go through some more fuses if you think there is a better place than another to start looking for, which would help save some time. (The fuse box that is next to the steering wheel, where you had me check before, or one of the boxes under the hood?)

I did find out from the previous owner that he went into the box that’s located in the rear window so he could disable the on-star unit. He had some conspiracy theory on why that item needed to be disabled. I don’t know if that grouping of items could affect the HVAC system, but the HVAC Definitely worked after he manipulated that item. So why would it affect it later?
He just said that he put a blocker over the pins of the OnStar, so that when it goes back together, there is no connection for that one particular ability.

I hope this doesn’t throw a bunch of additional things at us. But if it gives you any ideas, then that’s why I mentioned.

Also, I did have the dash apart so that I could fix one of the buttons on the stereo, and this required me to have the center council around the shifter, also the HVAC unit, and the nav screen area, completely opened up. I had a couple of the large plugs under the glove bog area unplugged as well.

Could one of the systems that I unplugged under the glove box area have been plugged back into the wrong spot when it was re-assembled? I remember having it disassembled for a couple weeks, then went back and reassembled everything from memory 3-4 weeks later. (I did party in college, and I remember second guessing which large cluster plugs went where, during reassembly.

I feel bad that I didn’t bring this up before, but I didn’t think that the HVAC plug would have been an issue since I saw that power flash when I ran my scan.

Call me names if you wish, I’m fine with them if they are deserved. I’ll stop here and wait for your input with this new knowledge I have thrown up all over you. My apologies, but seriously, all the thanks possible for your help here. I don’t know where to go/start from here.

Best
JH

I’m not sure you understood what he placed tape over.
Answer me this. Would the module in the rear dashboard/rear window, near the brake light in the center of rear window. Would that module have anything to do with the HVAC?

Would the HVAC Module be under the glovebox by chance?

The only thing manipulated in that rear window module was the “OnStar” connector. That one part that powers the OnStar system, had its ability to get power, taken away.

That should not, and did not affect the HVAC System, because the HVAC system worked fine after that modification.

Can you confirm that there in fact is a major connection or process done through that rear module that would/could, affect the HVAC at all. And if so, why would it be affected after a period of months of it working fine?

Is it more probable that there is a module that could have been affected under the glove box area, or in the guts of the center council, near the shifter area: region/quadrant.

Thanks for not calling me names, I was hoping to add some humor to my fricken headache with this thing.

To make things worse, I just had an issue with one of my other vehicles, making the Impala just become much more needed yet.

Defrost is very difficult in MN yet this to me of year. It’s still in the low 40’s to mid 30’s in the mornings.
Maybe tell me how I could diagnose the HVAC head unit as being good or bad.
How would one go about that process?

If you could answer these series of questions in your next response, that would be really helpful.

Thank you in advance.