ac not working

The first thing to do is check the wiring behind the radio, see where and damage may have been done to the wiring for the heater a/c system. If a shop installed the radio, take it back to them.

Check the fuse at the fuse box and the fuse strip mounted outside of the fuse box. If the fuses are OK, then its most likely the blower motor resistor, which is mounted under the blower motor, which you gain access to by removing the windshield wiper assembly. Best price on fan motor resistors is autohaus az.com