We live in Austin, TX where the temperatures can reach 100-105 degrees during the summer. My 2007 CLK550 Cabriolet A/C will not adequately cool the car. We have returned the vehicle to the dealer several times and have been told that the air conditioning is doing all it can do. The temperature of the air exiting the vents under similar conditions is consistently three to four degrees warmer than temperatures vent temperatures in the dealer's loaner cars. The dealer has evacuated and recharged the system while repairing "leaks." I am concerned that the problem may be one of several issues. First, the suction pressure control may be unloading the compressor prematurely. Second, the compressor may be undersized. Finally, the evaporator may be undersized. This is the first automobile that I have had since 1956 that had inadequate air conditioning! Help!