Ok, so I have a 2000 Escalade. The rear air blows cold but the front air does not.

Air blows thru vents properly.
Temperature control **** works properly.
Air blend door actuator works properly.
Air blend door movement is good.

I don't have access to an a/c manifold guage set, but can/will buy one if necessary.

What else is there to look into?

What is the discharge thing called inside the HVAC box. I replaced one of those things on a Mitsubishi Montero and the air conditioner began working properly.......but in all honesty, I replaced many of the Mitsubishi a/c parts. That being said, I can't pinpoint the part that was actually at fault in that particular situation.

Well, if the rear air is working, there should be enough of a charge in the system.....

You say the temp door is working......

I am thinking you are talking about the thermal expansion valve?