Yet another no heat/ac thread.... I know, I know.

[JonnyTahoe]

Since it is digital, I looked up again at RA for you. Does it look like this: https://www.rockauto.com/en/moreinfo.php?pk=950661&cc=1415551&jsn=905&jsn=905

Goes for $139.79. Found it at Amazon for $350 plus.

My Yukon has a hole in the back of the center console where that little control panel is suppose to be. You solved the mystery of what goes in that spot

 

[jwth]

Ok guys, I know you've seen this a million times but trust me I've researched the hell out of this and I've hit a wall.

03 Yukon Denali. I had the typical no temp change on the driver's side, in my case the AC worked fine but heat did not. Ok for the time being but it's about to get cold in CO so I need to get this figured out. So off to the forums I went and I saw thread after thread of this and the general consensus was the blend door actuator on the passenger side. Easy enough. Replaced that and it still didn't operate, it just cranks itself to the cold side just like the OEM one did and gets stuck there. After recalibration (pulling fuse, on/off, jump on one foot, spin 3, not 4, 3 times, yada yada) I still experienced the same symptoms but now the air will only blow on floor mode....great now I've got two actuators bad!! So yesterday I do this process a few more times along with some profanity and eventually I get everything to work as it should. Both temperature and mode are operating, such a relief! Nah, that'd be too easy!! I get in this morning and it's back to blowing cold on the driver's side again. WTF!! And not to mention the back doesn't have heat either but I haven't even dug into that yet but after this experience I'm sure looking forward to it.

Any thoughts on what could be going on? I've verified the blend door functions as it should. I know the core is working because when I manually turn the blend door it works as it should (both hot and AC work on both sides) and both hoses get super hot. Coolant level is topped off. One thing I find VERY interesting is in every recalibration video/write-up I see it says after pulling the fuse the digital screen will default to 74, well mine defaults to 75 so I'm not sure what's going on there.

So idk if my system is just cursed or what but my head is spinning. Any ideas would be greatly appreciated. I just bought the vehicle a few weeks ago so I'm blind as far as what has been worked on or not.

Ok I know this most likley wont help but I had the same problem on my 03 yukon and finally reprogrammed the system with my tech2 and tis2000.
Since then I have had no issues.

 

[Diesel6point6]

Ok I know this most likley wont help but I had the same problem on my 03 yukon and finally reprogrammed the system with my tech2 and tis2000.
Since then I have had no issues.

Anything helps, I appreciate any and all input! If putting a new module in there doesn't fix it I will probably resort to finding someone with a tech 2 to take a look. Man I've been reading lots of reviews on this Dorman brand one that's in there now and it's bad review after bad review, with some having the same symptoms I'm having. I may be giving myself false hope, but I've just about convinced myself that's the issue. At least I'll have the peace of mind even if it doesn't fix it and I can comfortably move on to the next step.

 

[brichter]

I asked about the Duramax to see which generation it is, you're an excellent candidate to own a Tech-2 and remove the guesswork from your repairs.

Are you selling one?

 

[OR VietVet]

Are you selling one?

They are on ebay all the time.

 

[swathdiver]

Are you selling one?

Nope, just suggesting that it is the most important tool you can own for working on these things.

 

[jwth]

Many modules for replacement need to be programmed or reprogrammed to get them to work with the new vehicle they are being installed in. Different vehicle, different controls and trim styles or packages. Not uncommon to get a "dumb" module that would fit several models with different controls.

 

[brichter]

Was looking for one, wound up with the vxdiag nano USB adapter and installed the software on a laptop I had laying around. Was going to get a Tech2, but this setup does GDS2 also.

 

[PNWYukon]

My 2005 Tahoe with Rear A/C stopped blowing hot air. I found a dude on youtube that showed how to diagnose that it was the controller module, not the blend door.

You jump a couple wires and can make the blend door move and it proves the controller module is dead. For the interim I jumped the blend door to open, then unplugged it. I have hot air 24/7 coming out of the rear system. I think that module is around $80-90 for the rear.

 

[Diesel6point6]

Ok guys, I finally have this issue solved! Nothing drives me more insane than doing my due diligence and searching threads, only to find 80% of them don't take the time to update what the issue was, so here's mine.

I first started with getting the correct part # actuator in there. With that, it was still acting very random. Would work one day and wouldn't the next so I was even more sure it had to be the control unit.

Although it took longer than I would've liked, I finally acquired a new oem HVAC control unit from the junkyard. I plugged that bad boy in with my fingers crossed, first with the original actuator that came with the vehicle just out of curiosity. That did not work. Next I put in the new actuator and we had lift off!! I can't tell you how relieved I was, this issue has been driving me insane.

So, all in all I had both an actuator problem as well as the control unit. If anybody reading this down the line has a Dorman brand aftermarket control unit, ditch it. Total junk that caused way more issues than it should have.

Thanks again for all that chimed in with advice. Now on to figuring out the rear heat