Chrysler Repair: 2000 Dodge Grand Caravan - AC, dodge grand caravan, grand caravan

Question
I recently had the entire Air Conditioning system repaced (I think ($800.00). The freon leaked out after less than 4 weeks. The rear blower is not as cold as the front (even with new freon), and the 3-way switch, located on the dash only works in the 1st & 3rd positions, with no difference in blow power. The 2nd position doesn't work at all. I trust my mechcanic, but they are at a loss to explain it. They put more freon and dye in today, in the hopes to locate a possible leak. Any suggestions?
Thanks, Robert in Kentucky

Answer
the entire system was not replaced only a little bit could u tell me what they did replace. As far as them not finding where the leak is  i cant do anything for u for there lack of experience in finding the leak. The blower motor issue would be a resistor more then likely.