HVAC Woes - 2006 Silverado 2500HD

[pcarenthuz]

Preface - I have worked my best to determine if there are any similar sounding posts to mine.

I have a 2006 Chevy Silverado 2500HD Duramax with the digital/'dual zone" controls (Pax and driver). Generally, a great truck. About 1 month ago, the heat "appeared to go out" while I was on a trip. What was really happening was the mode moved to defrost, and the drivers blend actuator moved to let only cold air blend in. This is the big picture issue. Mode defaults to defrost (as it should when there is an issue) and the driver's side blend actuator is fully CW and thus letting only cold air on the driver's side. The passenger side heat works fine, meaning it blends appropriately, but is "stuck" on defrost too (obviously since it shares the same mode actuator.

A bit more technical detail: both the mode actuator and drivers side temp blend actuator move to full CW position upon calibration and never appear to cycle back CCW. When this happens, 5vdc appears on pin 9 and I never see 2.5 volts (CCW) or zero (do nothing)

I have gotten very familiar with troubleshooting and testing:

1. Performed all the recalibration steps with disconnecting battery, removing the 10 AMP HVAC fuse, to set things up for recalibration.
2. Replaced the HVAC module with one made by Dorman
3. Bought an Autel scanner
4. Subscribed to Alldata (have all the schematics, etc)
5. Replaced the two actuators with new ones, reindexed them to ensure resistance was equal CCW and CW.
6. Went to the Chevy dealer and had them apply Service Bulletin 06-01-38-003 which is supposed provide more leeway with the calibration by loosening the tolerances to accommodate door wear (foam deterioration, etc)
7. I can manually manipulate the mode cam selector and move between defrost, vents, and floor. LIkewise, I can manually manipulate the driver's side blend door so functionally, I have heat and it works independent of the automation.

So ultimately, this is a bit of hail Mary post. I am thinking I may have a short somewhere. Have looked at some of the bulletins on this and have looked for chafing at noted places in the bulletins.

Thanks in advance.

Pat Arnold

 

[TJBaker57]

Bought an Autel scanner

Does the Autel scantool display live data for both the commanded and actual actuator position counts?

 

[pcarenthuz]

I'm no expert with the Autel but I did look at this data on a couple of occasions. I appreciate you asking. Let me go back and be more deliberate about what I'm doing.

Should I look at this when I have the actuators set to neutral (12 o'clock) or does it matter?

Thanks again.

 

[mrrsm]

Welcome Back to GMT Nation...

What a Thoughtful, Well-Considered Post...

I'm going to follow on in agreement with @TJBaker57 with the idea that the Latest Autel Line of Scan Tools may not have the dedicated Electrical System Diagnostics and Bi-Directional Controls that say a Legacy "GYMKO" Tech 2 or even the VXDIAG-NANO Tech 2 Emulators have that can utilize the TIS2000 -SPS Discs for Calibration Updates, if any such are called for on a GM Vehicle approaching it's 20th Birthday.

I dialed in your particular vehicle into my Snap-On Vantage Pro Tool... just to Demo the value of using a Two Channel Oscilloscope in order to *Spy* TTGs (Tiny Transient Glitches) that can never be visualized by a typical DMM.

This Snap-On Graphing Multi-Meter and its Two Channel Oscilloscope Tool takes 8 Million Samples Per Second made possible with a 12 Bit Resolution Feature. A Basic Hantek Model # 1008C (8) Channel Oscilloscope (8 Bit) will do the very same thing for Analyzing subtle loss of circuit continuity issues with enough DETAIL to be able to catch these events at play.



Since I know this might be -=Thinking a Little TOO Far Outside of The Box=-, You might want to take a swing my chin. But honestly, lately I've discovered that my "Offline AI Oracle" called Nomic GPT4ALL when loaded with the Llama 3.1 Large Language Model (LLM) that has an Eight Billion Token Trained Corpus, *IT* really seems surprisingly knowledgeable. So with that in mind, I Copy-Pasted your First Post Opening Paragraph into its Prompt Line ...thusly:



And -=THIS=- is what *IT* responded with in reply:



If you want more information on How To Use an Oscilloscope for Automotive Diagnostics, visit THIS Link for more examples, videos and hands-on demonstrations done by Eric "O" from SMA (South Main Auto) up in Avoca, NY, Paul "Scanner" Danner from Rosedale College in PA... Keith Defazio of "New Level Auto" up in Staten Island, NY and likewise, "Crazy Ivan" from Pine Hollow Auto Diagnostics, PA.

As per @TJBaker57 's observation... This was borne out recently, by Ivan (The Man From PHAD) after he discovered and posted a YouTube Video that essentially describes:

"Sometimes ...When it comes to GM Module re-calibration Reads & Writes...Only an Old School GM Tech 2 will work..."

The exception to this reality has proven to be the Autel Maxi-DAS DS708 Scan Tool which is now as Rare as Hen's Teeth to find on eBay in Good Working Order. See the YT Videos done by Keith Defazio of "New Level Auto" where he proved that:

"The, "Updated, Newer" Autel Scan Tools have been Dropping Support for Older GM Models" ...over time.

How To Use PICO #2204A & HANTEK #1008C Oscilloscopes

You don't need a Huge Bag of Coins in order to obtain and use an Oscilloscope for performing In-Depth Wave Form Analysis in Automotive Applications on everything from Problematic Electronic Fuel Injection to obtaining accurate Compression Tests to Diagnose Internal Engine Conditions. HANTEK...

gmtnation.com

And for the "How - To" on Downloading, Installing and Using GPT4ALL Completely FREE... These Links will assist you:

gpt4all at DuckDuckGo

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PS:

If it were me and with personal experience to back up this suggestion... I would be looking for a Snap-On Modis Diagnostic Complete Kit covering models and makes as close to the 16.2 Version Software Update as possible in the $550-$700 Range as per THIS GMT Nation Thread:

Snap On modis eems300 vs tech2 (first impressions)

The other day I spent some time with my new to me modis and went through my trailblazer to see what the modis can do compared to the tech2. So let's begin! 1) Modules - Right out the gate I noticed no onstar or radio selections. Normally with audio problems I get codes from the radio first...

gmtnation.com

 

[pcarenthuz]

So many emotions when processing your reply @mrrsm! Firstly, thank you as there is a ton of information here.

Ironically, I just sent a VXDIAG-NANO back as I found their software provenance just a bit too much to deal with and the licensing patch they sent me sent up some red flares.

Thank you for taking the time to look through your Snap-On. I hear you, if you are channeling this, I may need a pro with pro grade tools to sort this out. I'm totally open to that but trying to find someone with the inclination to get involved w/ this thing has been a challenge.

Finally, the GPT4ALL results are interesting for sure. Particularly, the part where it suggests the ECU may need to be reflashed.

Thank you!

 

[TJBaker57]

I'm no expert with the Autel but I did look at this data on a couple of occasions. I appreciate you asking. Let me go back and be more deliberate about what I'm doing.

Should I look at this when I have the actuators set to neutral (12 o'clock) or does it matter?

Thanks again.

What I would want to see is if the actuator(s) move to the positions commanded by the HVAC control module.

Even my $40 Autel AP200 does indeed display these live parameters.

If the actuator(s) 'counts' do agree with the commanded 'counts' then the issue is not the actuator(s).

 

[TJBaker57]

For my TrailBlazer I can graph the actuators commanded and actual positions so I can see the actuators all do as they are told.

I do this with some amount of trickery in a smartpone app (not the Autel AP200)

 

[pcarenthuz]

What I would want to see is if the actuator(s) move to the positions commanded by the HVAC control module.

Even my $40 Autel AP200 does indeed display these live parameters.

If the actuator(s) 'counts' do agree with the commanded 'counts' then the issue is not the actuator(s).

I'll get after this morning. I have an Autel MX9600 and I know I was messing around in this area of the software. Thanks for this.

 

[pcarenthuz]

For my TrailBlazer I can graph the actuators commanded and actual positions so I can see the actuators all do as they are told.

I do this with some amount of trickery in a smartpone app (not the Autel AP200)

View attachment 115751

That's slick. I will see what the Autel informs me of.

 

[pcarenthuz]

I was able to confirm with Autel Live Data reporting, my previously stated situation:

Autel Air Mix Right Door Command is PASSENGER SIDE
Commanded value and actuals track as they should and the Autel graphing depicted a nice trace of these.

Autel Air Mix Left Door Command is DRIVER'S SIDE
Commanded Value is 196, actual value is 197. These do not change

Mode Door Actual 0 (never changes)
Mode Door Motor Command 128 (never changes)

PWM/Fan Motor works as it should, functionally and tracks accordingly on the Autel scanner

Air Inlet (recirc) door works as it should

Mode Select position works, on the HVAC display as it should and registers correctly in Autel (Value == Bi-level, etc). Functionally, per the above Mode actual and commanded, it never moves off of defrost.

 

[mrrsm]

If you have no objection to this "AI Third Party" continuing to be part of this Diagnostic Thread... I'd once again like to Copy-Paste your last Post #10 into "GPT4ALL", since I saved your last conversation with *IT* ...and see how it responds after picking up where You and *IT* left off... Let Me Know...

 

[pcarenthuz]

Zero objections, sir.

 

[mrrsm]

Sorry for the Delay... A Nature Call... A Coffee Re-Heat and a few Post Answer Screen Edits using the Gnome Graphical Editor to tidy up appearances were involved.

The GPT4ALL response time after Pressing the <E> Enter Key happens at normal conversation speed ...with a typical "Human-Like" pause afterwards... allowing for the time that *IT* is actually THINKING about how to organize *ITS* Thoughts and render a decent explanation:



I forgot to mention this before...But... If your vehicle has been parked and idle for any length of time, particularly during the Cold Months where "Critters" may have invaded the innards of the Under Dash Cavities to get Warm & Cozy and Breed... pull the Cabin Filter and look for signs of Nesting Materials and Nuts, Food Remnants ...and do so with extreme caution in such confined spaces. Internal Nesting Blockages can STOP Blend Doors from moving, too.

North American Rodents like the ubiquitous Deer Mouse present nationwide (and Canada) as well as the Cotton Rat in the southern states are carriers of the Deadly HANTA and BLACK CANAL Virus Infections that can make Covid-19 look like a Common Cold.

HANTA (HPS) Infections come with the same symptoms as Covid that can rapidly lead to crippling, long term debilitation after a short incubation period ... and will result in DEATH with nearly 40 % of those infected. Google the story of what happened in the Desert Southwest of the USA involving what they called the "Sin Nombre" Killer Virus and that story will inform you of just how bad things can get.

Sin Nombre virus - Wikipedia

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1993 Four Corners hantavirus outbreak - Wikipedia

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Before fiddling around down there to Pull The Cabin Filters and causing friable Virus Laden desiccated Urine, Saliva and Feces powders to become airborne... Wear wrap-around Clear Eye Protection, M11 Nitrile Gloves and a properly fitting N-95 Mask. Keep a can of Spray Lysol at your elbow and use it on suspicious surfaces. Clean surfaces with Wet Naps and Towels.

Better to be Safe...than Sorry. Do NOT use Compressed or Canned air... Vacuum Only and dispose of the "Findings" of Nesting Materials and Turds, etc. with a Spray of Lysol and placement of the proceeds you find inside of Zip-Lock Bags. Keep Family Members, Pets and Strangers well away if you discover these issues are present prior to the Clean Up Efforts.

cdc hanta at DuckDuckGo

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[mrrsm]

*Bump* for important edits...

 

[pcarenthuz]

Thank you for running my findings through GPT4ALL. Similar output was had by ChatGPT, however, GPT4ALL trended a bit more completely/technically/accurately with the reported output:



I have confirmed the mode cam, and the driver's side door all move as they should when I manually manipulate them. No doubt, rodents can wreak quite a lot of damage, but I don't seem to have that issue here.

 

[pcarenthuz]

@mrrsm, earlier in this discussion, you mentioned a Snap-On scanner, is this what you were thinking (ACK the price is outside of the range you suggested)?

SNAP ON MODIS ULTRA 22.4 DIAGNOSTIC FULL FUNCTION SCANNER 1980's-2022! EEMS328 | eBay

Modis Ultra Main Unit with the Most Recent Current Software 22.4. Asian = 1980's - 2022.

www.ebay.com

 

[mrrsm]

Yes.... THAT Version of the Snap-On Modis is the Next Step Up with a larger between-year options covering a very wide range of vehicles and with the last update of that particular machine being the Version 22.4 it was probably topped off as far as Snap-On Updates would allow for that particular version of these very high end scanners.

Caveat Emptor (Buyer Beware)

Make certain to perform your Due Diligence by contacting the Seller within the eBay Messaging Service and obtain as many additional qualifying images of that Scan Tool Operation as possible and eliminate any notions that it has hidden defects not described on the sales page.

The advantages of course are multi-fold (manifold...? X>) ...) with having (1) The Scanner (2) The Two Channel Oscilloscope (3) Guided Component Diagnostics and (4) A Dual Digital Graphing Multi-Meter with a larger screen having Touch Screen capabilities that my "Elder Modis" Does NOT support, since it was outfitted with the earlier Microsoft CE Operating System that did not involve such features.

However... If your Pockets & Wallet are Deep Enough ...and the messages hidden within your GMT Nation Nick-Name bearing out your love of Cars and Diagnostics would suggest this... THAT Machine will be worth every Penny. Go to YouTube and watch as many of the Snap-On Modis Ultra Training Videos available to obtain more and better information about what a Truly Pro Grade Scan Tool Kit and System like THIS One can do for you:

THIS Video fits your present diagnostic needs...

Once you own it.., You can start "Walking Through The Tall Corn... With The Big Dogs" when performing Automotive Diagnostics ...like you would never believe possible.

 

[TJBaker57]

Mode Door Actual 0 (never changes)
Mode Door Motor Command 128 (never changes)

This right here looks like a mode actuator failure, or mode actuator wiring failure, no?

The actuator is being commanded to go to a position different than its' current position and it fails to do that.

 

[Mooseman]

Autel Air Mix Left Door Command is DRIVER'S SIDE
Commanded Value is 196, actual value is 197. These do not change

Mode Door Actual 0 (never changes)
Mode Door Motor Command 128 (never changes)

Neither of these commanded values change if you change them on the HVAC module? And to confirm that you have the automatic type with the two knobs and digital display?

 

[pcarenthuz]

This right here looks like a mode actuator failure, or mode actuator wiring failure, no?

The actuator is being commanded to go to a position different than its' current position and it fails to do that.

I'm thinking I must have a wiring failure. The Mode actuator goes full CW (it's where it is stuck now). And the Mode Door Motor Command value never changes either.

 

[pcarenthuz]

Neither of these commanded values change if you change them on the HVAC module? And to confirm that you have the automatic type with the two knobs and digital display?

Correct, neither commanded values change. Affirm, I have the automatic type with the two knobs and digital display.

 

[pcarenthuz]

...

Once you own it.., You can start "Walking Through The Tall Corn... With The Big Dogs" when performing Automotive Diagnostics ...like you would never believe possible.

Sounds intriguing. I wish I had come here first before buying the Autel because I would indeed like to walk through the tall corn!

 

[TJBaker57]

I'm thinking I must have a wiring failure. The Mode actuator goes full CW (it's where it is stuck now). And the Mode Door Motor Command value never changes either.

If the mode door commanded value does not change in any/all positions of the mode switch I would further suspect controller failure.

The mode door commanded value should change in relation to the desired mode naturally.

And the mode door actual should in turn go to match the commandd value.

 

[Mooseman]

I agree with @TJBaker57 . After inspecting the wiring and determine there is no damage, you can try and find a used HVAC module/control (the panel) from a same year truck from a pick-n-pull yard. I would imagine a gas truck of the same configuration (i.e. crew cab) would work. If you get one new/rebuilt or one from a different configuration, it will have to be reprogrammed.

 

[pcarenthuz]

I agree with @TJBaker57 . After inspecting the wiring and determine there is no damage, you can try and find a used HVAC module/control (the panel) from a same year truck from a pick-n-pull yard. I would imagine a gas truck of the same configuration (i.e. crew cab) would work. If you get one new/rebuilt or one from a different configuration, it will have to be reprogrammed.

Mooseman and TJBaker57, I did purchase a new Dorman HVAC controller, and it exhibits the same outcome -the two actuators not working properly. This said, I have not monitored it with the Autel like I did the original GM unit. Sounds like I should do that to capture commanded and actual values.

Also, I'm not being dismissive of getting an actual GM HVAC controller replacement so I will do that if the Dorman units are known not to be a consistently reasonable replacement.

 

[Mooseman]

Mooseman and TJBaker57, I did purchase a new Dorman HVAC controller, and it exhibits the same outcome

It needs to be programmed. Either at a dealer or a shop with that capability. If trying yourself, you would need a J2534 passthrough tool and a subscription to ACDelco's TDS. Maybe your Autel scan tool is capable of this? The vast majority don't.

 

[pcarenthuz]

It needs to be programmed. Either at a dealer or a shop with that capability. If trying yourself, you would need a J2534 passthrough tool and a subscription to ACDelco's TDS. Maybe your Autel scan tool is capable of this? The vast majority don't.

Super interesting thank you for that information. I was not aware of this. With the Dorman installed, the Autel recalibration doesn't do anything. You have to force a recalibration through the 10 AMP HVAC fuse removal/wait/reinstall sequence and then power + defrost (IIRC) and then select the right configuration through the blower up control.

 

[Mooseman]

With the Dorman installed, the Autel recalibration doesn't do anything.

That's because the new module doesn't have the required software to be able to do anything. It's like a new computer without an OS.

 

[pcarenthuz]

That's because the new module doesn't have the required software to be able to do anything. It's like a new computer without an OS.

Okay, got it. I was unaware of that. The other day when the dealer installed the SB (against my factory controller) I mentioned in my opening post he made it sound like that SB had an affinity to the HVAC controller which I assumed was more or less a firmware release. I guess the same controller was used in a variety of vehicles and the software you mention is likely specific vehicle configuration type options.

 

[mrrsm]

These suggestions come from an "Old School" Diagnostician... but are in concert with your own developing suspicions and worth mentioning for the Readers and Followers of this Hard-2-Diagnose Problem:

 

[pcarenthuz]

I appreciate you sharing this. There is some sage advice here for sure. Need some warmer Wx, however. I do want to take a bit of a fresh approach including the great ideas, counseling, and suggestions here with you all. Thank you!