2002 chevy express 3500 climate control replaced and a/c not working. Won't change from vent to the defrost and a/c won't turn on. Voltage to a/c compressor not turning on.

2002 chevy express 3500 climate control replaced and a/c not working. Won't change from vent to the defrost and a/c won't turn on. voltage to a/c compressor not turning on.

Was the control head diagnosed as causing the A/C to be inop?