Is300 A/c Temperature/thermostat Sensor

[mooingchicken]

So im having a little problem, My a/c works fine with hot and cold, but there is really no in between. if the temperature is set to 16 or 16.5 degrees (the lowest two settings) it blows really cold, but as soon as it goes to 17+ degrees it changes over straight to hot air.

This all started when the standard stereo was replaced with a 2 din dvd/nav system. So i think in the process the thermostat was either unplugged by accident or broken/damaged. The battery was also disconnected so maybe there is a temperature setpoint stored on the computer which might need to be adjusted?

I have pulled the glove box out to look at the fan and see if i could see anything disconnected, everything looks connected and fine, there are 2 black boxes mounted against the drive train tunnel, which appear to be the attenuators for the temp and the vent selection, both seem to be working fine, but the temperature one switched from fully open to fully closed as soon as u switch from 16.5 degrees to 17, which im not sure if this is normal or not.

also if anyone knows where the temperature sensor is located that would be alot of help also