[busboy4]

Wow

Scratching my head with you. Since you have a cold-to-the-touch freon line inside at the back unit, I'm going to assume for the moment that the rear evaporator is getting cold. If that is true, then I would think you are either not getting airflow through the evaporator due to clogged fins, or your blend door is not really working properly and some of the airflow is passing through the rear heater core too. Since you do have a cold freon line I am also assuming at this point that you have normal freon flow through the rear unit. I could be wrong on all accounts. However making those assumptions for the moment gives you a direction to go : check the rear blend door and make sure it is moving - I think I have heard of the linkage breaking internally. The actuator goes back and forth, but is really accomplishing nothing. You will probably have to remove and/or disconnect the actuator so you can manually manipulate the blend door linkage (Of course I am also assuming this is possible). Beyond that, I would think checking the evaporator for flow would obviously require taking the rear unit apart to visually inspect it, which may be too much.

One oddball thought: Shadetree technique for proper freon charge has been "equal temp on the freon line into and out of the evaporator." If the line out is warm freon charge is likely low. I would think it unlikely that your front unit would be working top notch if the overall charge were low, however since we are grasping: How much freon did they add after the compressor replacement? I will have to look up the quantity, but if memory serves, the '96 with rear air is around 31/2 pounds.