These are the codes the Topdon Topscan gave me below.
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B0418: Temperature Control #2 Feedback Circuit Range/Performance

• Issue:
  
  • This code indicates a problem with the passenger-side blend door actuator, which controls the mix of hot and cold air for the passenger-side vents.
• Likely Replacement Part:
  
  • Dorman 604-106 HVAC Blend Door Actuator
    • Used for the passenger-side blend door (temperature control).
    • Confirmed for compatibility with the 2005 Hummer H2.
• Location:
  
  • Located on the passenger side, below the dashboard, typically under the top of the dash near the right of the center console.
  • Access may require removing the dash top for full visibility and replacement.

B0229: Airflow Mode Door Range/Performance

• Issue:
  
  • This code indicates a problem with the mode door actuator, which controls the airflow direction (e.g., defrost, vent, floor).
• Likely Replacement Part:
  
  • Dorman 604-121 HVAC Mode Door Actuator
    • Used for the mode door, responsible for airflow direction.
    • Matches typical location and function for the Hummer H2.
• Location:
  
  • Located on the driver’s side, to the left of the steering column, near the HVAC housing.

 

Thus far it turns out it was my recirculating actuator and the right temp actuator. I mistakenly bought a mode actuator. The upshot of having this part handy made me understand that someone had already replaced the actuator for the passenger side but had used a mode actuator. There is a difference in the rotating gear. The recirculating actuator was hell to replace because the Dorman housing is a little bigger and there is a latch on it that also gets in the way. Because you're kind of doing this blind I could not figure out why I couldn't get this one to fit other than there is no room for error, it is so snug in there. So that's when I took out my calipers and started comparing, realizing I was comparing to a different kind, etc. There is one MODE actuator, two temp (LEFT and RIGHT) actuators and one RECIRCULATION actuator. The MODE has a metal shaft. The other three are identical and have a plastic shaft. Since I didn't have to do the mode, I don't know what kind of pain it is. As for the plastic thing that falls out, I'd probably use a little duct tape to keep it in place before I remove the mode actuator.

There was no advantage to having the head unit out to access the RIGHT actuator. And if you look at the OEM directions they expect you to remove the entire dash instrument panel, which is why the charges for replacing these is outrageous. Get a headlamp and definitely spend $30 on a Borescope. I used the Borescope to locate all the nuts then used it as a flashlight while I felt around with my hands (which are now quite scraped). I posted photos of the Dorman issue for the recirculating replacement here: https://www.hummerforums.com/forum/h...52/#post412764

I got the parts from Napa, which are Dorman in a Napa box.