I too am having this problem.
Compressor is running Hi/Low pressures sides are hot/cold. A/C will start to blow somewhat cold when I turn on the car, but with in 45 seconds switch to hotter than ambient temperature. I think it's the Blend Door Actuator, but there has been mention of a module (I assume a piece of electronics) that could be bad as well. There is also mention of an Evap Sensor, but since the compressor is running, I don't think it is this. I have also seen in this thread mention of disconnecting the battery, what does this actually do? Why would it work?
Is there a way to diagnose which part is actually bad?
Edit. I went and stuck my head by the Blend door Actuator and had my girlfriend move from hot to cold. I can hear it move from hot to cold and back. Sounds like it flutters for a second then switches back to heat when switching between from cold to hot. It will also stay on cold for a little longer when moving from hot to cold on knob slowly. In the end it always goes back to the hot position for some reason.
