92 gm sierra climate controls not working

[scotttyra5361]

I have a 92 gm sierra 1500 that the climate controls have quite working. The unit doesn't display anything. Hence no fan no nothing. Fuses are all good, fusible links at firewall are all good. There is a 12 v constant, 12 v ign, good grnd and 5 v wire at the controls plug. They all test out properly. I purchased a used set of controls from e-bay, plugged them in and still nothing. I could sure use some advice on which direction to head and what to check.

Thanks for any and all help.