I have a 91 Silverado k1500. It has the push button AC and heater control panel. The panel does not function - no fan - no heat - no air - no lights in the panel. The part number label is no longer on the panel but it is the style with the "RECIR" button rather than the "MAX" button (part # 16204785).
I installed a used 16204785 (max button style) and found the same results. No function - no lights in the panel. I am told the replacement panel was tested aand worked.
There is current showing at some of the connector points on the truck side connector plug.
I have cleaned the connector points on the back of the panel and in the plug connection.
I have checked the fusable links near the fire wall and all seem fine.
I have checked the fuses under the dash and all are fine.
There are three relays behind the glove box. I think one or more have something to do with the AC. I have heard buzzing from these relays in the past but this has gone away. The panel did not work at all before or after the buzzing problem.