Chrysler Repair: 1997 T&C lxi air conditioner, c control, lxi

Question
I have a 97 T&C with a 3.8L that the air conditioner in the rear section is not cooling.  I was told by the dealership that the A/C control head needed to be replaced.  Is there a simple test that I can perform to let me know if the control head is defective?  Also today, the air in the front of the van stopped cooling.  It worked fine when I took it in to the repair shop, but when I got it back, it didn't cool.  I was wondering if the two problems I am having might be related and what things could possibly be causing them.

Answer
Usually when you lose the rear air first you are low on charge.Its further away from the compressor so you would lose it before the front.I wouldn't suspect the control head right off.There is a self diagnostic test that you can run on the control head.However it won't pass because you are low on charge.I would check for leaks and charge the system up and go from there.