last year my heater/ac lighted ***** started to get dim, soon after the air was only coming out of the bottom vent. when i turn dial the air only comes out the botton vents(bad for winter defrosting). meanwhile the heater/ac still works fine, now the lights are totally out. so at night i have to turn on dome light to see *****. at first i was told maybe my blend door is bad, now since my lights are out i was told maybe the whole dash unit is bad thats why vents are not working. i hate to go to dealer and they rake me over.
i have a 2005, 2500 diesel

 

as for the lights they are just small bulbs but as you activate the blend **** you can see the servo arm move it if moves then your door is broken, pretty easy fix though and the new ones are metal from rock auto. And if your recirculate door is broken too you can r&r is by just removing the blower motor