I have a 2004 1500 Silverado and the heater ac controls were working then all of sudden the heater and the fan are the only thing not working. The light for the ac does not come on when you push the button. When you push the rear defrost button is pushed nothing happens. The slide temp doesnt change the temp the vent defrost feet **** changes nothing. I Changed this unit about a year ago. Everything was working shut the truck of when i turned it back on it was not working. Is there a way to test to see if its bad or any suggestions or any help would be appreciated.

Here is what my unit looks like.