2005 Tahoe, Z71, 5.3 normal gas, not flex.
My initial problem was the A/C on the drivers side was blowing HOT, while the passenger and rear blew cold.
Through this site and others, I found that the Blend Door Actuator needed replaced. I have done this, along with the AC pressure switch which was also recommended. I also checked the refrigerant level and its measured full.
I have gone through the steps of re-calibrating the HVAC multiple times, but it will only blow hot regardless of what setting its on.
I also disconnected the battery for a couple hours in hope it might reset everything.

HELP!?!?!??!

 

When it blows hot, shut the engine off, restart, is it back cold? If so, since you replaced the actuator, did you have it set to the stem correctly, the slot in the actuator can be 180 off to the actuator to door stem.

 

I have done pretty much everything possible. Shutting down, restarting, unhooking battery, replaced/swapped out fuses, no luck. Cannot get it to cold.
The new actuator was positioned to the default position and it slid right into the stem coming out from under the dash. My assumption is that its set correctly. I have tried going all the way to hot as well to see if its reversed, but still hot.

 

I replaced an actuator on our 2005 Yukon with a Dorman replacement. Like with a GM actuator, had to get the Yukon to "learn" the actuator.

Now here is the tricky part that I had to research. Thanks to a site called Sparky's Answers, I was able to figure this all out and pass it onto everyone here. Now supposedly if you have a scan tool you can adjust and calibrate the actuator thru the scan tool. Since I don't, he also gave information on how to calibrate without a scan tool. So here ya go. First once you get actuator, new or used, make sure it can not move (I mean the metal know shouldn't be able to move by hand and differently don't move with pliers), if so, it is probably bad, if not go ahead and install the way it comes, and reconnect wiring. Then you will disconnect the battery for at least 30 seconds. Then reconnect battery, turn the ignition to the ON position for at least 1 minute, but he suggested 3-4 minutes so that's what I did, and DO NOT TOUCH THE A/C CONTROLS!!! You will then turn ignition to the OFF position for at least 10 seconds, then start the engine and confirm the new actuator is working correctly by turning the climate **** from cold to hot. If all was done correctly it will work!! I checked the actuator by being on the passenger side, turning ignition on, moving climate ****, and sticking my head under dash to watch for the actuator to move.

 

Just to confirm:
-when turning the ignition on for 3-4 minutes like you did, should the HVAC controls be in the off position?

 

I think "off". It's been quite a while.

 

I tried your recommendation twice, no luck!