I have a 2009 STI with a problem since the day I bought it, every time the temperature outside gets really cold and I'm driving on the highway the cabin of my car overheats. When the car is parked in their shop the dealership technicians stick a thermometer in the vents then say the temperature is normal, they do not test it in the cold or on the highway.
Today it was -19° Celsius (2° Fahrenheit) and I had to open my window a little to cool down the cabin of my car while I was driving on the highway. If I set the temperature knob to 20° Celsius my cabin overheats however if I set the temperature knob to the next setting (absolute coldest) then it just draws in fresh really cold air from outside and I freeze, there is no in between setting.
Does anybody have any ideas what might be causing this problem, my wife doesn't want to ride in the car because it gets so hot and the dealership technicians have no interest in fixing the problem.
Winter has just started and I'm already frustrated with the car!