2004 Yukon XL (Suburban, Silverado, etc) Dual Climate Mix Door

The dual climate temperature control on our old Yukon has been getting worse and worse.  While driving the temperature will randomly change, usually drifting toward full heat mode which isn't very convenient in the middle of a Texas summer.  The temperature is controlled by a pair a doors that mix air coming across the heater core with air coming across the air conditioning evaporator.  The doors positions are controlled by motorized actuators and those actuators are where the problem lies.  

The actuator for the driver's side is relatively easy to access and repair/replace.  On the passenger side, remove the black cover underneath the glove box above the footwell by removing the three screws.  The left one is ridiculously hard to access but I was able to eventually get it out with a 6mm deep socket and a 1/4" drive ratchet.

Passenger Side with Cover Removed
Driver Side Mix Door Actuator can be seen on the left with the little red wiring connector

Once the cover is off the actuator can be removed with two screws then just pull down to slip it off the door shaft.

The passenger side actuator is whole different story.  The factory replacement procedure goes something like this: "remove the dashboard, remove the air conditioning controls, remove the radio, remove the air bag (be careful!), remove the OnStar controller, now you can access the actuator."  If you Google how to replace the passenger side mix door actuator on this platform of vehicle, you'll find a simpler process advocated in various forums that goes something like: "Take the truck out into a field, pour gasoline on it, strike a match (be careful!)."

Since neither of those alternatives sounded like what I wanted to tackle on a Saturday morning, I took a different approach.  If you pull the glove box stop tab back and let the door flop down out of the way and look up towards the center of the vehicle, you can see the passenger side actuator sitting on top of the air box assembly.  I turned the temperature up and down, fan off and on, etc until I was pretty sure that the mix door was closed in the full air conditioning position.  At that point, I took an extra long screw driver and pushed up and in on the wiring harness connector latch to disconnect the wiring.  

Looking up and towards the center of the truck through the glove box (with it out of the way)
The actuator can be seen with the bar code sticker.
The wiring connector can be disconnected with an extra long screw driver reaching up from the bottom.

 My passenger side now has no possibility of heat, but in Texas that is much preferable to not being able to turn off the heat.  In the summer I'll have A/C on both sides and in the winter I'll only have heat on the driver's side

--->  Fixed (good enough) in about 90 minutes for free.