W208 CLK430 Climate Control Help

[stim141]

Having some issues with my climate control. Did the standard diagnostic test with the unit and it doesn't throw any codes.

Did the sensor readings and temps/electrical readings are normal BUT have an issue with the ambient (outside) temp reading. When driving normally above 40mph the reading pretty much matches the gauge cluster temp. When sitting after car has been driving the reading is WAY high - 145 and even during a short idle the temp will shoot up from normal. This is a problem because the climate control seems to think its really hot outside and will switch on the ac and blow cold air into the cabin. The interior temp reading shows about 78/79 when the climate control is set at 74 or 75 and will never drop unless you really lower the temp. Seems like its callibrated a few degrees greater than the unit.

Took the car into the dealer and they seem very confused. Gave him my readings. They think by ordering a new climate control unit will solve the problem.

QUESTION: Is the ambient temp gauge reading correctly - or should it pick up the heat from the engine compartment? Where is it located so I can check it myself to see if its plugged in correctly or fitted to the appropriate inlet?