A/c Problem

[01dtt]

I have 2007 ES350 and I think the car A/C is not working correctly. but I told the Lexus dealer many times and they said it's normal.

When the outside temperature is 77oF (displayed on the information screen) and I had A/C temp set at 74oF. In the front air vent, the cold are is blowing out - and it's what it's supposed to be. However, the air vent in the backseat didn't have any air at all (sometime, it blowed out the hot air too - I guess because the temperature difference between the ambient and the car setting temp). And the A/C air setting is not dual. I found it's weird that the air temp in front and back vent are different. The lexus dealer said that 74oF is the car setting for hot air... I don't buy it because regarless what the hot temperatur setting is the air in the front and back vents should be the same. I can't convince them about thinking... so I still stuck with that problem (so either people in front seat have to freeze to death or the backseat passengers have to suffer - because if the outside temp is 77oF, the car A/C temp has to set at 70oF or below)

Did your car has problem like this?