Greetings all. My 92 Surburban 5.7 L has great heat WHEN the controler (the digital temp/blower speed, Etc.) will come on, currently it's dead, nothing, only panel lamps (behind switches) work, there is no digital display, and the blower motor will not come on, 0. The rear blower will spin (L,M,H) BUT is only cold air (rear control is in the roof console, both drivers, and 2nd row controls.) I've checked all fuses that I can find, and speedo works (same fuse I'm told). It's like the control head is NOT getting power. I've opened the actual head and the circuit board has no "burnt" parts, it looks ok, and no overheating marks. I understand there are 2 blower relays but where they are I have no idea.