I have a 2004 E500 with 30K miles. The a/c blows very cold, but when the interior is already hot, the drivers side vents only blow moderately cold air, unlike the passenger side. If I turn the a/c off, then to auto, it is a little better, but still not really cold. There is no differance to the temperature, when I lower it to the coldest setting on the driver's side. But if I set the drivers side to "Hot" the vents then do put out hot air and will return to the moderate temp after returning the setting to cold. When the car's interior is already cold, it is fine. This just started about 2 weeks ago. Any ideas?