climate contron not working

2000 bravada 4.3 smart trac. no power to any of the climate controls ....blower motor speed...vent selector... a/c button ...rear defog. all fuses are good connections at blower motor are clean and tight. i have heard that it could be a modual. when i checked for parts to fix i was told that it might be the entire control system [3 knobs] or a a/c modual . the price is $145 for a/c and $275 for controls. lot of money to play a guesing game .no available parts at junkyard around here. any input would be helpful. thanx! new here at this site hope i posted in the correct place.

You need to use a digitial multi meter or some other voltage tester to actually test the wires going to the climate control panel to see what is happening. Could be something simple as a blower motor resistor or something more severe as the modules. What exactly is happening? How have you testing parts?