I am new to Mercedes and had a question about the rear a/c blower. My 2006 ML 350 has the dual zone climate system. I know when the rear system is off the red light is on in the front control in the rear button. I like to leave the rear system on when it is hot out to put a little air in the back seat area. Pushing the button on the front control turns the light out and the rear button in the back says auto and air blows from the rear vents. My question is every time I start the vehicle the red light is on in the front rear button indicating that the rear system is off. Does this default to off every time you shut the vehicle off? If after starting the car I push the button the rear system comes on and works fine. I thought that the rear system would stay on , and come back on after each startup without having to push the switch. In fact this is how it worked until yesterday. The owners manual tells how to turn it on but does not say anything about it defaulting to off. The only info it says is on real hot days the system will cool the front area better if the rear is switched off. Does this system turn on and off due to heat load or do I have a problem with something. If a Mercedes tech or owner could let me know it would help me out.