There Are 4 fuses you can check..
Looking at the Diagram for the Bravada, It ' s a Very complex system controlled by the BCM, (Body Control Module) ..
The Fuses will be a 15 amp ECM "B", A 20 amp ECM 1, An A/C Heater Fuse 25 Amp, And A Gaug/Ins Fuse..
The BCM controls those two Electrical functions so If it's out, they (as well as some other functions you haven't noticed yet) Will be out..
Try the fuses first, and see if they cure the problem, If not, you'll have to bring it back and let them work their magic on it..(unless you want a course in advanced Electronics.)
Hope Your Son is OK, and the Bravada Works out for him..My Brother Has one and just loves it.