My W203 2005 model cooling/heating system has worked fine for almost 8 years now except 1-2 years ago when the A/C wouldn't blow cold air anymore. A refill fixed that problem. This evening the heating system worked fine when I drove to a friend of mine. 3-4 hours later I started the car to drive home and the Thermatic panel, that used to light up, stayed black. The Thermatic panel doesn't respond to any of the buttons except the A/C OFF button. If I press that button the A/C OFF red LED lamp will light and the Thermatic panel will light up also...but that's all. When I press defrost button I can hear something move inside the dashboard, but no fan start and no LED light turn on. The Thermatic panel is same as the ACoff-REST (third from top) here http://mbworld.org/forums/attachmen...303089-new-mods-manual_hvac_control_units.jpg Suggestions on how this can be fixed is highly appreciated.