The next step is to improve the A/C condenser coils under the hood.  The factory ones on the earlier Hummers have a low heat exchange ratio compared to some of the coils out now.  The newer coils are Serpentine tubes type coils called as to the older round style tube type coils. Surface area for the Serpentine tubes type coils are 4 to 6 times the area compared to the tube type coils and work much better.

This here is the old style coil stack.  As you look at the photo, you will see the cooler for the power steering on top of the old type AC coils.    (click on photo for larger image)
Here you can see there are four levels for cooling coils. 
Click on photo for larger image.
This here is the old tube style type coils and as you can see the surface area where the liquid is the outside of the round tube. The round tubing is in two layers, with both upper and low levels meeting at the finals before going to the dryer for the AC unit. In my option, this condenser coil was not designed right. It should have an upper and lower runs, with the upper set being the final run to the dryer that should be the coolest.
Here is the flat ribbon type coils (Serpentine tubes). The tubes that carry the liquids to be cooled is in the flat tubes that go from left to right.. The flat tubes are the depths of the whole coil (about 1 inch) and have many times the surface area for cooling compared to the old style above. The aluminum fins are connected to the surface rib type coil to help in the heat exchange. The flat tubes run from one end, to the other, and then exit to the dryer.
In the photos here, is the 97 factory upgrade kit.  The newer coils are shorter front to back, so with this newer coils. So they relocated the power steering cooling coils so that they sit at the bottom of the new AC coils.   (click on photo for larger image)
One other item that I did was to add a valve to the heat supply line to make sure that no heat water enters the heater coils. 
Here is a cross view of the flat ribbon type coils, called Serpentine tubes.  Something like this set of coils is what I will be installing soon.
My next step is to find a good Serpentine tube type coils to replace the stock coils I have, and to replace the dryer with a larger unit.  The larger dryer will also help in better cooling by giving the system a larger volume in which the freon can expand better.