05 Burban A/C problem Dealer cant even fix
 

I have an 05 Burban 2500 the the front A/C does not work in. I have had it to the dealer 6 times and the cost total so far is at 2360 dollars and it still doesnt work. The rear air is fine the front has had all the actuators changed. The blend door actuator twice, as well as re calibrated 3 times it has no heat or A/C, the temp blows a constant temp consistent with the outside air. If you put it on heat it makes alot of noise but no heat comes out (same for A/C)
The dealer said they cant do anymore for it they "just cant find the problem"
They suggested I try a dealer that has more techs as 1 of them may be able to help.
The A/C cycle switch has been changed to. They took the whole dash out and replaced the blend door itself and the wiring harness(s). They also took out the headliner and replaced and recalibrated that thing above you head for the climate control.ANYONE?

"The noise" you hear is the key.......can you describe it? I have my suspicions but need more info.

Did they replace the A/C control head?

A/c control head (auto climate control) was replaced
The noise I am talking about is just the air coming out of the vents at a high rate of speed to I guess tease me?
It is at the 2nd GM dealer now 56 miles away and as of yesterday at 3pm they have no clue either.